Turn broiler on high. Blacken the poblano and bell peppers to char skins evenly all over. Place in a bowl,
cover and cool. Peel, seed and stem the peppers, and place in food processor.
Line a rimmed baking sheet with foil and spray the tomatillos, onion and garlic with cooking oil. Season with salt and pepper, and char under the broiler until onions soften a bit and tomatillos blacken and burst, about 10-12 minutes. Place veggies in the food processor with the peppers along with the nuts, cilantro, parsley, mint and vinegar. Add salt and pepper, and pulse-chop into a fine mixture while streaming in EVOO. Remove to a container or bowl and reserve.
For the steak, heat a large, cast-iron skillet over medium-high to high heat. Cut steak into portions to fit in pan. (Meat can be cooked in 2 batches depending on pan size.) Season meat with salt, pepper, cumin, coriander and granulated garlic. Heat oil, 1 turn of the skillet. When pan smokes, add beef and cook until crispy and brown on both sides.
Serve steak sliced topped with Romesco sauce and a simple salad of baby kale tossed with shaved Manchego, lemon juice, EVOO and salt alongside. Add cracked or chopped olives and pimiento if you like.
The Romesco sauce keeps up to 3 weeks refrigerated and is great on any protein or charred bread or sandwich.