Mix taco seasoning with 2 tbsp of chicken broth to form a loose paste. Add chicken and turn to coat.
Heat 1.5 tbsp oil in a large skillet over medium-high heat and cook chicken 3 minutes each side until golden.
Remove chicken and shred it.
Lower heat to medium, add tomato paste, sugar, remaining broth and scrape out remaining taco seasoning paste from bowl.
Stir and simmer, then add shredded chicken and simmer to reduce to a thin syrup.
Serve in tortillas or crispy taco shells topped with diced onion, tomato, avocado, lettuce, coriander and a dollop of sour cream.
