Heat oil in a large skillet over medium-high heat until shimmering. Add onions and peppers and cook, stirring frequently, until softened and well-browned, about 10 minutes. Add chorizo and cook, breaking it up with a potato masher or whisk. Continue cook until meat is cooked through, about 5 minutes.
Drain excess fat and return pan to heat. Add sugar and tomato sauce and cook, stirring, until reduced to a sauce-like texture. Stir in hot sauce and season to taste with salt and pepper. Spoon mixture into toasted burger buns, top with avocado and onion, and serve.
Note: Store-bought fresh Mexican chorizo can be used in place of the homemade. Remove from casings before using. Store-bought salsa verde can be used in place of homemade.
Recipe and Photo from www.seriouseats.com