Steak and Jalapeño Tacos

Heat broiler. Rub steak with chili powder and season with salt; set aside. In a pan over medium heat, heat oil; cook jalapeño and half the onion,stirring frequently, until soft, 8 to 10 minutes. Remove from heat and cool to room temperature; transfer to a blender or food processor and process with Worcestershire, lemon juice and 2 teaspoons salt until just blended. On a broiler pan, broil steak, flipping once, to desired doneness, about 5 minutes for medium-rare. Transfer steak to a cutting board, let rest for 3 minutes and cut into 1-inch strips. Divide steak among tortillas and top each with 1 tbsp jalapeño sauce, plus remaining onion, cilantro and avocado. Serve with lime wedges.