Preheat the oven to 375°. Spray each of 24 muffin cups, rather generously, with cooking spray. Spray tortilla quarters on both sides. Place one quarter in each cup and bake for 10 minutes, until the edges are golden brown. Remove from the oven.
Remove casings from chorizo. Cut into 1/2 inch slices and fry until well browned. Drain Set aside. In a bowl, whisk eggs until blended. Whisk in milk, cilantro, ground chile, and salt until well blended. Set aside.
Evenly divide the chorizo among tortilla-lined cups. Top evenly with egg mixture and then with cheese and onion rings. Place 4 chile strips on each tart with tips together in the center and strips radiating out to the edges. Set tarts on center rack of oven and bake 15-20 minutes, or until egg mixture is firm.