Preheat oven to 400°
Line a baking sheet with foil.
Peel tomatillos, rinse and rub sticky coating off tomatillos.
Place tomatillos, onion halves, garlic, chilies on baking sheet (no need to peel onion or garlic before roasting).
Roast in oven for 20 minutes, turning once.
Once roasting is complete, peel garlic and onion.
Add tomatillos, onion and garlic to food processor and pulse.
Cut and remove seeds from chilies.
Add chilies to food processor. Pulse.
Add cilantro, lime juice, diced tomatoes and pulse until desired consistency is reached.
Salt to taste.