Blend avocado, jalapeño, water, cilantro, white vinegar, and salt in a food processor until smooth (1-2 minutes). Refrigerate salsa.

Preheat oven to 400°F (200°C). In a bowl, combine chicken thighs, olive oil, chili powder, cumin, smoked paprika, garlic, cilantro, poblano peppers, and onion. Toss until coated and spread in a baking dish. Bake for 20-22 minutes until cooked.

Let chicken rest before shredding into bite-sized pieces, mixing with poblano and onion.

Raise oven temperature to 425°F (220°C). Bake corn tortillas for 5 minutes to soften. Add cheese, shredded chicken mixture, and more cheese on tortillas before folding into tacos.

Bake tacos for 15-17 minutes until crispy and golden brown.

Cool slightly before serving with salsa on the side.