Cook chicken on stovetop by heating 1 tbs. olive oil in a sauté pan over medium heat. When hot, add pre-marinated chicken breasts "pretty" side down first and cook for 5 minutes. Flip carefully right-side up and cook another 4-5 minutes.
Remove from heat, tent with foil and let rest for at least 5 minutes before slicing.
Mix together greek yogurt and taco seasoning, adding a splash of water if sauce needs thinning. It should be the consistency of mayo.
Clean pan you used to cook chicken with a paper towel, then heat again over medium high. Place one tortilla in and heat for 15 seconds then flip and repeat.
Working one burrito at a time (unless you have someone helping!), spoon half of crema onto tortilla and spread evenly. in the center of tortilla, layer chicken slices, avocado slices, 1/2 can black beans, shredded cheese and sliced jalapeños.
Roll burrito by folding one end towards the other. Fold in the opposite two ends towards the center, then roll tightly ending with seam-side down. Place back into hot skillet for 2-3 minutes per side to seal burrito and toast!