You can use ground chicken or turkey in these burgers. The vegetables mixed into the patties keep them moist, while the cumin and crushed red pepper add just the right amount of spice. Top with lettuce, tomato and creamy avocado for an easy and satisfying meal.
Preheat a 12-inch cast-iron skillet, grill or large grill pan to medium-high heat.
Heat the oil in a small skillet over medium-high heat. Add the shallots or onions, bell peppers and 1/2 teaspoon salt and cook, stirring occasionally, until the vegetables are soft but not browned, about 1 minute. Transfer to a medium bowl and set aside to cool for 2 minutes.
Add the ground chicken or turkey, cilantro, the lime zest, 2 tablespoons of the lime juice, 1 teaspoon of salt, 1/2 teaspoon black pepper, the cumin and crushed red pepper to the bowl with the shallots and bell peppers. Mix well with your hands until combined. Divide into 4 equal mounds and form each into a 1-inch-thick patty.
Cook the patties until the internal temperature reaches 165 degrees F, 3 to 4 minutes per side.
Meanwhile, combine the avocado with the remaining 1 tablespoon lime juice and 1/2 teaspoon salt in a small bowl. Lightly smash the avocado with a fork to combine.
Top the bottom buns with the lettuce, patties, tomato slices and mashed avocados. Close the burgers and serve.