For Salsa: roast whole tomatillos, unpeeled garlic and onion on a dry griddle, turning often, until charred and fragrant, about 10-15 minutes. Toast chiles on dry griddle until blistered and fragrant – be careful not to burn them, or they become bitter. Soak chiles in very hot water for 10 minutes until they are soft. Drain. Peel garlic and place all ingredients in blender container. Process until almost smooth. Add salt to taste. Reserve.
For meat: butterfly beef pieces so they open like a book. Cover with plastic wrap and pound until they are ¼” thick. If pieces are too large, cut them in half or quarters. Rub meat pieces all over with lime juice and sprinkle them with salt and pepper. Let sit 5 minutes.
Heat a cast iron griddle or pan over medium high heat and add 1 tsp vegetable oil. Cook meat pieces for 2-3 minutes per side. Remove meat to a cutting board and let rest 5 minutes. Serve immediately with salsa, lime wedges, whole beans and flour tortillas.