Step 1

Cook oil and garlic in a large saucepan over medium heat until garlic is golden brown all over, 6–8 minutes. Spoon out garlic with a slotted spoon; save for another use or discard. Add peanuts to oil and simmer until golden brown, about 2 minutes. Transfer to a small rimmed baking sheet with spoon. Cook pasilla chiles in oil just until slightly puffed and darkened, 30–60 seconds. Transfer to baking sheet with peanuts. Repeat with ancho chiles, then chiles de árbol. Let oil cool slightly.

Step 2

Transfer peanuts and chiles to a food processor and pulse until coarsely chopped. With the motor running, stream in oil and purée until peanuts and chiles are finely chopped, about 1 minute. Season salsa with salt and let cool.

Step 3

Serve salsa macha with tostadas, avocados, herbs, and lime wedges.

Step 4

Do Ahead: Salsa can be made 2 months ahead. Cover and chill.