In a large bowl, combine the ground beef with chili powder, cumin, garlic powder, onion powder, salt, and black pepper. Mix until just combined.

Form the mixture into 4 equal-sized patties, making a slight indentation in the center of each patty.

Preheat a grill or skillet over medium-high heat.

Cook the patties for about 5-7 minutes on each side, or until they reach your desired level of doneness.

In a separate skillet, add a little oil and heat over medium heat.

Add the sliced bell pepper and onion, sautéing until they are tender and slightly caramelized, about 5-6 minutes.

In a small bowl, mash the avocado and mix it with sour cream and lime juice until smooth.

Toast the burger buns on the grill or in a toaster.

Spread a spoonful of avocado cream on the bottom half of each bun.

Place the cooked burger patty on the bun, top with sautéed vegetables, lettuce, and tomato.

Finish by placing the top half of the bun on the burger and serve immediately.