Aromatic Oils

Have you noticed how adding garlic or onions to soups and stews doesn't really add much flavor? Thousands of recipes tell you to do it. But you're mostly wasting them. The flavor in your aromatics doesn't dissolve in water. It dissolves in fat.

The science: why water fails

The aromatic compounds in garlic, ginger, scallions, and shallots dissolve into fat. They do not dissolve meaningfully into water.

Most of what makes garlic, ginger, scallions, and shallots taste like themselves is fat-friendly. The compounds responsible for garlic's characteristic punch (diallyl disulfide, diallyl trisulfide, allyl methyl sulfide, the specific molecules your nose detects when garlic is sharp and pungent) strongly prefer fat over water. Scientists measure this preference with a number called log P, which compares how well a compound dissolves in fat versus water. Diallyl disulfide has a log P of about 1.6, which means it dissolves into fat roughly 40 times more readily than it dissolves into water. The compounds that give fresh ginger its brightness (zingiberene, bisabolene, both terpenes, the category of fat-soluble aromatic molecules found in most herbs and spices) behave the same way. So do most of the fragrant compounds in scallions and shallots.

When you simmer aromatics in water, only the water-friendly fraction comes out: amino acids, mineral salts, trace precursors. Enough to taste faintly of the ingredient. The compounds that make garlic taste like garlic and ginger taste like ginger stay locked inside the cells. There is no fat present to dissolve them. Sautéing in oil first, or finishing with an infused oil, is not a stylistic choice. It is the only way to actually extract these compounds into your food.

Two techniques

Fast & Hot (325 to 350°F)

Every aromatic ingredient is made of cells. Each cell has a membrane (a thin wall built from fat molecules) that holds its contents inside. At 325 to 350°F (163 to 177°C), two things happen at once. The cell membranes rupture from the sudden heat. The rigid cell walls weaken. The intracellular contents (all those fat-soluble flavor compounds that water cannot touch) spill directly into the surrounding oil, which is right there to dissolve them.

Hot oil also extracts faster than cool oil because heat speeds up how fast molecules move. The hotter the liquid, the faster dissolved compounds can travel through it. This means extraction that would take minutes at room temperature happens in seconds at frying temperature.

Exposure time is deliberately short. The volatile compounds (the ones responsible for bright, fresh top notes) begin to evaporate and break apart at sustained high heat. Twenty to thirty seconds of active sizzle extracts the flavor. Longer cooking destroys it.

How to tell the oil is ready: dip a wooden chopstick into the oil. Steady bubbles streaming up around it means it is hot enough.

Low & Slow (200°F)

To understand the low and slow method, you need to know one thing about garlic. Raw garlic's sharpness comes from a two-step chemical process. When a garlic cell is damaged by cutting, crushing, or chewing, an enzyme called alliinase (an enzyme is a biological molecule that triggers a specific chemical reaction) contacts a compound stored in the cell called alliin and converts it into allicin. Allicin is the compound responsible for the burn and the aggressive raw-garlic smell.

At 200°F (93°C), alliinase breaks apart from the heat and stops working. This is called denaturing. Proteins (and enzymes are proteins) unravel when they get hot enough, the same way a raw egg white turns from clear to solid when you cook it. Alliinase starts to denature above 167°F (75°C). By the time garlic reaches 200°F throughout, it is completely inactive. Allicin production stops. The sharpness disappears entirely. What remains is the garlic's underlying sugars and its milder, rounder aromatic compounds.

At the same time, the pectin that holds garlic's cell walls together (pectin is the natural structural glue in plant cells, and it is also what makes jam gel when you cook fruit with sugar) slowly breaks down under sustained heat. This softens the garlic from the inside out, which is why confit garlic becomes fork-smushable. As the cell walls soften, fat-soluble flavor compounds diffuse gradually into the surrounding oil over 25 to 30 minutes. Because the process is slow and gentle, deeper aromatic compounds that a quick extraction never reaches have time to migrate out. The result is richer and more layered than the fast method, at the cost of the bright top-note character that rapid extraction preserves.

A 200°F oven works just as well as an air fryer for the recipes below. The air fryer preheats faster and circulates heat more actively, but the temperature and timing are the same either way.

My four favorite oils

1. Scallion-Ginger Oil

Cantonese · Fast & Hot · Vivid green · ~1¼ cups · Active: 8 min

Ingredients

• 1 cup neutral oil (peanut, avocado, or vegetable)
• ¾ cup scallions, finely chopped (white + green)
• ¼ cup fresh ginger, grated
• 1 tsp kosher salt
• 1 tbsp light soy sauce (added after)

Method

1. Place scallions, ginger, and salt in a 4-cup Pyrex measuring cup.
2. Heat oil in a small pan to 325 to 350°F. Wooden chopstick test: steady bubbles mean it is ready.
3. Pour the hot oil over the aromatics in one continuous stream. It will sizzle for 20 to 30 seconds.
4. Cool 10 minutes. Stir in soy sauce.
5. Transfer to a mason jar. Refrigerate.

Use on

Hainanese chicken, steamed fish, rice, noodles, dumplings, scrambled eggs.

2. Smoky Paprika Garlic Oil

Spanish · Fast & Hot · Ruby red · ~1¼ cups · Active: 8 min

Ingredients

• 1 cup neutral oil
• 6 garlic cloves, lightly smashed
• 2 tbsp Spanish smoked paprika (Pimentón de la Vera if possible)
• 1 tsp dried oregano
• 1 bay leaf
• 1 tsp flaky salt
• ½ tsp red pepper flakes (optional)

Method

1. Place garlic, smoked paprika, oregano, bay leaf, salt, and pepper flakes in a 4-cup Pyrex measuring cup.
2. Heat oil to 325°F. Slightly lower than the scallion oil because paprika's aromatic compounds are more heat-sensitive and will burn above this temperature.
3. Pour over the aromatics. The paprika will bloom instantly into vivid ruby red.
4. Stir well. Cool 15 minutes.
5. Transfer to mason jar with everything in it. Refrigerate.

Use on

Fried eggs, hummus, avocado toast, roasted potatoes, white fish, popcorn, butter beans, Spanish tortilla.

3. Garlic-Rosemary-Lemon Confit Oil

Italian · Low & Slow · Golden amber · ~1¼ cups + spreadable garlic · Active: 5 min · Cook: 30 min

Ingredients

• 1 cup good olive oil
• ½ cup whole peeled garlic cloves (12 to 15)
• ¼ cup fresh rosemary leaves, stripped (~6 sprigs)
• ¼ cup lemon peel in strips (no white pith)
• ½ tsp red pepper flakes
• 1 tsp flaky salt

Method

1. Combine everything in a small Pyrex dish or oven-safe ramekin that fits your air fryer.
2. Bake or air fry at 200°F for 25 to 30 minutes until garlic is amber-golden and fork-smushable.
3. Cool fully.
4. Transfer to mason jar with all aromatics in it. Refrigerate.

What you get

The oil	Pizza, pasta, bread dipping, focaccia, drizzled on burrata
The garlic	Spread on toast, mash into potatoes, fold into hummus, swirl into pasta
The herbs + lemon	Leave in the jar. Keeps developing flavor for 2 weeks.

Chef's note: At 200°F garlic does not brown. It CONFITS. Alliinase deactivates. Pectin softens. Sugars concentrate. The result is honey-sweet, soft, and infinitely spreadable.

4. Smoky Shallot-Arbol Oil

Mexican-lean · Low & Slow · Amber-red · ~1¼ cups + soft shallot bits · Active: 8 min · Cook: 25 min

Ingredients

• 1 cup neutral oil
• 1 cup sliced shallots (4 to 5 medium, sliced ¼" thick, mandoline recommended)
• 2 dried arbol chiles, broken open (seeds in = hotter, seeds out = milder)
• 1 garlic clove, smashed
• 1 bay leaf
• 1 tsp flaky salt

Method

1. Combine all ingredients in a small Pyrex dish or oven-safe ramekin.
2. Bake or air fry at 200°F for 20 to 25 minutes. Shallots will go translucent and melty.
3. Cool fully.
4. Transfer to mason jar with everything in it (shallots, chiles, and bay leaf).

What you get

The oil	Fried eggs, fried rice, tacos, grain bowls, grilled corn, soup garnish
The shallots	Spoon out as a soft garnish on anything
The chiles	Keep in jar for visual effect and ongoing infusion. Gets better in week 2.

Pro touch: Toast the arbol chiles in a dry pan for 30 seconds before adding them to the oil. Dry heat triggers the Maillard reaction (a chemical reaction between amino acids and sugars that creates new flavor compounds. It is also why bread browns and meat gets a crust). In chiles, this produces smoky, roasty aromatic molecules called pyrazines that are fat-soluble and will infuse into the oil. Do not burn them. Pull when fragrant.