Procedures

1. 1

   Marinate Steak: Combine white onion, minced garlic, lime juice, cumin, and salt in the bowl of a food processor. Pulse until smooth. Place steak in a large zip-lock bag or baking dish. Cover with marinade and let rest in refrigerator for 2 to 4 hours.

2. 2

   Make Salsa: Roast tomatoes under a broiler until they've started to blacken and are soft and cooked through, about 12 minutes. Cool tomatoes then pull off blackened skin and discard.

3. 3

   In a small heavy skillet over medium high heat, roast serrano chilies and garlic (in their skin) until they have softened and begun to darken, 5 minutes for the chilies and 15 minutes for the garlic. Take off heat. When garlic has cooled, discard skins.

4. 4

   In a food processor, combine roasted garlic and serrano chilies. Pulse until smooth. Add tomatoes and pulse until almost smooth with a few chunks. Transfer tomato mixture to a small bowl. Stir in onions, cilantro, and lime juice. Season with salt.

5. 5

   Make Tacos: Roast poblanos under a broiler until black on all sides. Wrap in a dish towel and let sit for 5 minutes. Rub off blackened skin. Cut off stem and discard any seeds. Cut peppers into 1/4-inch strips.

6. 6

   Heat a gas grill to medium high or put a grill pan over medium high heat. Lightly grease grill with oil. Grill steak until medium rare, about 2 minutes per side. Let steak rest for 5 minutes then cut into 3 inch strips. Fill each tortilla with steak mixture, roasted poblanos, and salsa.