Ingredients

Method

Bring onion, tomatillo, jalapeño, garlic, and 2 cups water to a boil in a small saucepan. Reduce heat and simmer until onion is very tender, 6–8 minutes; let cool. Drain, reserving cooking liquid.

Purée onion mixture with avocado and cilantro leaves in a blender. With motor running, gradually add oil and 2 tablespoons cooking liquid and blend until combined.

Add lime juice; season with salt and pepper.

Prepare grill for medium-high heat. Grill poblano, turning occasionally, until charred and blistered, 6–8 minutes. Let cool. Peel and finely chop.

Drizzle cut sides of romaine with oil; season with salt. Grill, cut side down, until charred, about 3 minutes. Turn and grill just until warmed through, about 30 seconds.

Spoon dressing onto plates and top with romaine, charred side up, avocado, onion, and poblano. Drizzle with lime juice; season lightly with salt. Scatter Cotija cheese and chopped cilantro stems over.