Preheat the oven to 325 degrees .
In a medium bowl, combine the red onion, jalapeno, the juice of 1 lime and 1 tsp. agave. Season liberally with salt and pepper and toss to combine. Let stand a few minutes until juices form. Toss the pickled onions again before serving.
Meanwhile, in a large nonstick skillet, heat the oil, one turn of the pan, over medium-high. When the oil ripples and begins to smoke, add the chicken and cook, breaking up the meat with a spoon, until browned, about 3 minutes. Add the onion, garlic, coriander, cumin and cinnamon; season and stir to toast the spices, about 1 minute. Add 1/2 cup of the stock, the chipotle puree and 1 tsp. agave. Bring to a bubble, then reduce the heat to medium-low. Simmer, adding more stock if dry, until the flavors meld and the sauce thickens, 10 to 15 minutes. Stir in the remaining lime juice; remove from the heat.
While the chicken mixture is simmering, put the taco shells on a baking sheet and bake until golden, 5 to 8 minutes.
Fill the taco shells with the chicken, pickled onions, cheese, lettuce, tomatoes, cilantro and hot sauce.