Eggs, Rancher's Style: Huevos Rancheros
Heat 2 tablespoons of oil in a medium saucepan cook onion slices for 1 minute. Strain the pureed sauce into the saucepan with onion. Season with salt and crushed oregano. Cook over medium heat for 3 minutes. Keep mixture at a simmer. Have warm plates ready.
Fry tortillas in remaining 4 tablespoons of oil in a medium skillet. Drain and place 1 on each plate. Fry eggs in butter 1 at a time. Place eggs on each tortilla and cover with the sauce.