What each ingredient does, and what to do when you cannot find it.

Fermented anchovy liquid. Salty with a deep savory finish. Used in nearly everything.

Substitute

Light soy sauce (vegetarian), though you lose depth.

Storage

Pantry, years. Darkens over time but stays good.

Thick, glossy, sweet-savory. The body of most stir-fry sauces.

Substitute

Vegetarian mushroom oyster sauce.

Storage

Fridge after opening, 1 year.

Soft caramel sweetness. Sold in pucks or tubs. Rounds out salt and sour.

Substitute

Light brown sugar, slightly less.

Storage

Pantry. Microwave a hard puck for 20 seconds to soften.

Sour with fruit behind it. Buy the seedless block and soak it in hot water, then strain.

Substitute

Lime juice plus a pinch of sugar, added off heat.

Storage

Block keeps a year in the pantry. Strained paste, 2 weeks in the fridge.

Dense, salty, funky. A teaspoon in a curry paste or nam prik. Smells stronger than it tastes.

Substitute

Fish sauce, or skip for vegetarian.

Storage

Fridge, indefinitely. Double bag it.

Sweet, smoky roasted chili and shrimp paste jam. Tom yum nam khon and stir-fries.

Substitute

No good substitute. Worth buying.

Storage

Fridge after opening, 1 year.

Piney, citrusy, sharp. Sliced into soups, pounded into pastes. Tastes nothing like ginger.

Substitute

Nothing close. Frozen is fine, dried is not.

Storage

Freezer, 6 months. Slice before freezing.

Lemony, floral. Bruise and infuse, or slice the tender bottom third for pastes and salads.

Substitute

Lemon zest, in a pinch.

Storage

Fridge 2 weeks, freezer 6 months.

Intense citrus perfume. Tear into curries and soups. Slice hair-thin for salads and fish cakes.

Substitute

Lime zest, with less perfume.

Storage

Freezer, indefinitely. Use straight from frozen.

Peppery, clove-like. Only for pad kra pao and a few stir-fries. Wilts fast.

Substitute

Thai basil, knowing it will be sweeter.

Storage

Use same day, or freeze the leaves flat.

Sweet, anise-leaning, sturdy. Curries, drunken noodles, as a side herb.

Substitute

Italian basil, with a different character.

Storage

Stem in water on the counter, 4 days.

Small and very hot, fruity underneath. Pounded, sliced or smashed whole.

Substitute

Serrano, using more.

Storage

Freezer, 6 months. No need to thaw.

Earthy, more intense than the leaf. Pounded with garlic and white pepper as the base of marinades.

Substitute

Cilantro stems, doubled.

Storage

Freezer, 6 months.

Fragrant long grain. Rinse until the water runs nearly clear, cook with slightly less water than the bag says.

Substitute

Any long-grain white rice.

Storage

Pantry, 1 year.

Glutinous rice, soaked and steamed, never boiled. For Isaan food and desserts.

Substitute

None. It is its own thing.

Storage

Pantry, 1 year.

Sen lek (medium) for pad thai, sen yai (wide) for pad see ew. Dried ones get a cool-water soak, not a boil.

Substitute

Fresh noodles from an Asian grocer, used the same day.

Storage

Dried: pantry, 1 year.

Granite for pastes, clay with a wooden pestle for som tum. Pounding releases oils that a blender cannot.

Substitute

A food processor, with a splash of water. Results are a step down.

Storage

Rinse, air dry. Never soap a clay mortar.