Potatoes, Chorizo and Caramelized Onion Tacos - Rick Bayless

Ingredients

• 3 medium (about 12 ounces total) boiling potatoes (Yukon golds work well, but so do most of the ones I find at my farmers market)
• Salt
• 12 ounces (3/4 cup packed) Mexican chorizo sausage, casing removed
• A little vegetable oil, bacon drippings or fresh-rendered lard if needed
• 1 medium onion—white, yellow or red are all good—cut into ¼-inch slices
• 12 warm corn tortillas
• Roasted Tomatillo Salsa
• A ripe avocado (optional, but very delicious), halved, pitted, flesh scooped from the skin and cut into ½-inch pieces