Carne Asada Tacos

Name: Carne Asada Tacos
Ingredients: 6 garlic cloves, finely chopped; 1 cup (packed) coarsely chopped cilantro; ½ cup fresh orange juice; ½ cup Mexican pale lager (such as Modelo Especial or Corona); ⅓ cup fresh lime juice; ¼ cup extra-virgin olive oil; 2 Tbsp. Diamond Crystal or 1 Tbsp. plus ½ tsp. Morton kosher salt; 1 Tbsp. freshly ground black pepper; 2 tsp. apple cider vinegar; 2 tsp. ground cumin; 2 tsp. red chile powder; 2 lb. ¼-thick skirt or flank steak, cut into 5-long pieces; 3 Tbsp. extra-virgin olive oil, plus more for grill; 1 small white onion, halved; 2 serrano chiles, stems removed; 10 oz. tomatillos (about 3 large), husks removed, rinsed; 3 garlic cloves, sliced; 3 Tbsp. fresh lime juice; 2½ tsp. Diamond Crystal or 1½ tsp. Morton kosher salt; 1 tsp. freshly ground black pepper; ½ tsp. garlic powder; ½ tsp. ground cumin; 1 cup (packed) coarsely chopped cilantro, plus more for serving; Flaky sea salt; Warm corn tortillas, chopped white onion, and lime wedges (for serving)