Instructions

1. Purée cilantro, 1 tablespoon Worcestershire, plus soy sauce, garlic, poblano pepper, chopped onion, salt, and pepper in a food processor until smooth; transfer to a bowl along with beef and gently mix. Form mixture into six 6-oz. patties; chill.
2. Heat a 12″ cast-iron skillet on stovetop or grill over medium-high heat. Brush buns with butter or oil and, working in batches, cook until lightly toasted, about 1 minute; set aside. Add 2 tablespoons oil to pan; add cabbage, salt, and pepper; cook until slightly browned, 2–3 minutes. Transfer to a plate; set aside. Add 2 more tablespoons oil to pan and working in batches, cook sliced onion and tomato, flipping once, until slightly browned, about 3 minutes for onion and 2 minutes for tomato; set aside.
3. Whisk a tablespoon Worcestershire, the mayonnaise, relish, ketchup, salt, and pepper in a bowl; set aside.
4. Add remaining oil to pan and, working in batches, cook burgers, flipping once, until cooked to desired doneness, about 10 minutes for medium rare.
5. Serve on buns with cabbage, onion, and tomato; drizzle with the secret sauce. Serve the remaining sauce with the rest of the cabbage, onion, and tomato. Drizzle more as needed. These are deliciously messy burgers.