Make the Creamy Chimichurri Sauce by mixing Greek yogurt, mayonnaise, finely chopped shallot, fresh parsley, jalapeño, olive oil, red wine vinegar, minced garlic, and salt in a medium bowl.

Season the Chicken by patting dry and rubbing it with a mix of garlic powder, salt, and pepper. Let it rest for 10 minutes.

Cook the Chicken in a skillet with avocado oil over medium-high heat for 4-5 minutes on each side until fully cooked.

Sauté Jalapeño and Onions in the same skillet with a splash of water for 3-4 minutes.

Combine the shredded Chicken with the sautéed jalapeños and onions, adding chopped cilantro.

Build the Tacos by laying romaine lettuce, then chicken mixture, avocado, feta, and drizzle chimichurri sauce on each tortilla.