In a medium bowl, combine ground turkey, salt, black pepper, egg, diced onion, minced garlic, diced jalapeño, lime juice, and feta crumbles. Mix gently until just combined.

Divide the mixture into six equal portions and shape each into a round patty.

Heat olive oil in a skillet over medium heat, add three patties and cook for about 5 minutes until golden brown, then flip and cook for another 5 minutes until internal temperature reaches 165°F.

In a blender, combine cilantro, lime juice, sour cream, and a pinch of salt. Blend until smooth and creamy.

Toast the burger buns cut side down in the skillet for about 2-3 minutes until golden.

Assemble the burger by spreading cilantro crema on the bottom of each bun, followed by lettuce, a turkey patty, more crema, sliced avocado, and onion rings.

Serve and enjoy with crispy fries or a refreshing side salad.