Make the salsa verde: place tomatillos and jalapeños cut-side down on a baking tray. Grill under a hot broiler for 5–7 minutes until charred. Blend with garlic, onion, coriander, lime juice and salt until smooth. Taste and adjust seasoning.
Mix the cumin, paprika, garlic powder, chilli powder, salt and pepper. Rub the spice mixture all over the chicken thighs.
Heat oil in a heavy pan over medium-high heat. Cook the chicken thighs for 5–6 minutes per side until cooked through and slightly charred. Rest for 5 minutes, then slice or shred.
Warm the tortillas directly over a gas flame or in a dry pan.
Assemble: place chicken on each tortilla. Top with salsa verde, avocado, queso fresco and fresh coriander. Serve with lime wedges.