Place the tomatillos in the medium saucepan, cover with water, and set over medium-high heat. Bring to a boil, then reduce heat to medium and simmer for 8 to 10 minutes, until the tomatillos are soft and cooked through. Using a slotted spoon, transfer the tomatillos to the jar of a blender along with the cilantro, poblano, jalapeño, serrano, chicken broth, and salt. Puree until smooth.
In a medium saucepan, heat the oil over medium heat. Add the pureed three chiles salsa and let simmer for 2 to 3 minutes. Add the chicharrón in pieces and continue cooking for a couple minutes more.
Use it as a filling for tacos or quesadillas, or as a topping for sopes or pellizcadas.