Heat the coconut oil in a 10-inch cast-iron skillet over medium heat. Add the onions and cook until softened, 3 to 4 minutes. Add the garlic, cumin, coriander and 1/2 teaspoon salt; cook until the spices are toasted and the garlic has softened, 1 minute. Add the pinto beans, chicken stock and chipotle puree and bring to a boil. Cook until the stock has reduced by about half and the mixture has thickened, 5 to 6 minutes.
Off the heat, mash the beans to a smooth paste with a potato masher, leaving some beans partially mashed to add some texture. The beans should have the consistency of a thick sauce; if they're difficult to stir, they're too thick. If needed, thin the beans out with extra chicken stock, 1 tablespoon at a time.
Finish by stirring in the lime juice and adding salt to taste. Garnish with queso fresco and cilantro, and serve with lime wedges.
In this recipe it's important to use refined coconut oil, for its neutral flavor. Substitute vegetable oil if necessary.