2In a small dry pan, toast the Dried Chile de Arbol over medium heat for 1-2 minutes until fragrant, being careful not to burn them. Remove from heat.
3In a blender, combine the Black beans, the roughly chopped White onion, the roughly chopped Garlic cloves, the toasted Dried Chile de Arbol, and the Epazote. Add 150g of Water (or reserved bean cooking liquid). Blend until very smooth. If the mixture is too thick, add a little more Water until it reaches a pourable consistency.