Dice the chicken thighs into 1 inch chunks. Cook on high heat with lots of oil to brown. Add the onion and cook a few more minutes. Meanwhile, process the vinegar, chipotles, and syrup until smooth. Pour that mixture onto the chicken. Scrape the bottom of the pan a lot to get the built up browned bits off the pan. Keep stirring and bring to a simmer. Simmer until the liquid has reduced to a glaze like consistency.

Heat up the tortillas, pop on some chicken, avocado, cojita, salsa, and cilantro. Eat it!