Prepare the oven and baking sheet: Preheat the oven to 425°F. Line a baking sheet with parchment paper.
Cook the aromatics: In a large skillet over medium heat, melt the butter. Add the minced onion, garlic, and salt, stirring frequently until the onion turns soft and translucent (about 5 minutes). Stir in ½ teaspoon of cumin and ½ teaspoon of chili powder, cooking for another minute until fragrant.
Make the refried beans: Drain one can of pinto beans and add them to the skillet along with the entire contents (liquid included) of the second can. Pour in 4 sprigs of cilantro and 2 tablespoons of water. Bring to a boil, then lower the heat to medium and let the beans simmer, stirring occasionally, until thickened and resembling a gravy-like consistency (about 10 minutes). Remove from heat, discard the cilantro stems, and use a fork or potato masher to roughly mash the beans—some texture should remain. Adjust salt to taste.
Assemble the taco-dillas: Place one tortilla on the prepared baking sheet. Spread 3 tablespoons of the refried beans over half of the tortilla, then sprinkle 2 to 3 tablespoons of shredded cheese on top. Fold the tortilla in half. Repeat with the remaining tortillas, spacing them about an inch apart. Use an additional parchment-lined sheet if needed.
Bake until crispy: Lightly spray the tops of the tortillas with nonstick spray or oil. Bake for 10-12 minutes, or until the tortillas are golden brown and the cheese is fully melted.
Prepare the lime crema: While the taco-dillas bake, blend the sour cream with the remaining cilantro, lime juice, ¼ teaspoon cumin, ¼ teaspoon chili powder, and a pinch of salt. Blend on high speed until the mixture is smooth and flecked with cilantro (about 30-45 seconds).
Serve and enjoy: Plate the taco-dillas with the lime crema on the side for dipping and dolloping.