In a small dry fry pan over medium heat add the coriander and cumin seeds until fragrant and slightly toasted tossing frequently to prevent burning. Cool slightly transfer to a mortar and pestle or spice mill and grind.
In a large Dutch oven heat oil on a medium high heat. Add onions, garlic, cumin and coriander stir and sauté until onions are soft and translucent.
Add the oregano and bay leaves to the onion mixture stir to incorporate, then add tomato puree, chopped chipotle in adobo, and chicken broth stir and bring to a boil, add chicken thighs return to a boil, reduce heat to a simmer and cover with lid slightly ajar until chick is done. 40 minutes.
Preheat over to 400°
Remove chicken pieces from sauce, let cool slightly, debone and shred chicken with a fork. return to sauce cook for an additional 10 - 15 minutes. Remove from heat add vinegar and half of the lime juiced. Stir and cover.
Place tortillas in a Taco Shell baking rack, or simply fold in half and slip them over the grates on the oven racks, (if uses this method make sure your over racks are clean otherwise you may end up with unwanted debris in your tacos and the possibility of them sticking) Bake for 10 to 15 minutes until edges are toasted but the tortillas are still pliable.
Fill Taco shells with mixture add toppings (remaining onion slices, cilantro, pickled jalapenos and chopped tomatoes) and a squeeze of lime juice.... enjoy!