Place tomatillos, peppers, onions and garlic in a pot and cover with water. Heat over medium-high heat and simmer partially covered until tomatillos have changed color from a bright green to a dull green and have softened, about 15-20 minutes.
Remove vegetables from water and blend in a blender until smooth, about 30-60 seconds
Meanwhile, heat 3 tablespoons vegetable oil in a large skillet over medium high heat
Season ribs with salt and pepper
Once oil is hot, add ribs in batches and turn to brown evenly, about 3-4 minutes per side or 12-16 minutes total per rib
Place salsa and broth in a dutch oven or other wide pan and heat over low heat. Add salt to taste
Add the purslane and fava beans (if using) and stir to incorporate
Add the ribs to the sauce and allow to simmer an additional 15-20 minutes partially covered.
Divide among serving plates and enjoy warm