Make the beans:
Put the beans and the onion in a medium saucepan and cover with water. About a half inch over the beans. Bring to a boil and reduce to simmer. Add the spices and combine. Cook until the water evaporates and the beans are thick and creamy. Approximately 30 to 40 minutes. Stir frequently.
Preheat the oven to 375°
Dampen two paper towels and fold them over the corn tortillas and microwave for 1 minute and 10 seconds. This will make the tortillas malleable, so they won’t crack when you roll them.
Brush the outside of the tortilla with a thin layer of oil (optional, this will make the taquito crispier) and put two tablespoons of beans and a layer of torn spinach leaves on top and spread evenly on the tortilla. Roll it as tightly as possible and leave the seam side down. If you have trouble keeping them closed use a toothpick to hold them shut. Remove after baking.
Put the rolled taquitos on a baking sheet and bake for approximately 15 to 20 minutes or until they’re a light golden brown and they have a crispy surface. Let cool slightly before eating and remove the toothpicks if you used them.
Dip in guacamole or salsa and enjoy!