Flank Steak Fajitas with Guacamole

Name: Flank Steak Fajitas with Guacamole
Ingredients: 2 tablespoons ground cumin; 2 tablespoons garlic powder; 2 tablespoons onion powder; 2 tablespoons chile powder; 6 tablespoons olive oil, divided; 3 pounds flank steak; Kosher salt and freshly ground black pepper, to taste; 2 onions, sliced; 4 spicy chile peppers, seeded and sliced; 2 tablespoons olive oil; 3 ripe avocados, halved, pitted, peeled and diced; 1 small red onion, diced; 1 small tomato, diced; 2 cloves garlic, chopped; Juice of 1 Meyer lemon; 1 lime, juiced, plus 2 limes, zest and juice, divided; 2 cups sour cream