Prepare the tomato sauce first: Melt butter in a small saucepan over medium heat. Sauté minced onion, garlic, and oregano for about 5 minutes until fragrant and translucent. Add tomato sauce and 1/8 teaspoon salt, stir, reduce heat to low, and simmer gently while preparing the rest, stirring occasionally.

Prepare the peppers: Cut stem ends off jalapeños, carefully remove seeds (wear gloves), and rinse under cold water. Stuff each pepper with a piece of cheese (¼ inch wide/thick, 2 inches long).

Make the egg coating: Separate eggs, placing whites and yolks in separate bowls. Beat whites until stiff peaks form. To yolks, add 1/8 teaspoon salt, flour, and water; beat until flour is incorporated. Gently fold beaten whites into yolk mixture without deflating.

Fry the rellenos: Heat vegetable oil in a large, heavy frying pan over medium-high heat. Create four mounds of egg mixture in the pan. Place a stuffed pepper in each mound and cover with more egg mixture to form nests. Fry for 3-4 minutes until bottoms are light golden brown, then carefully flip to brown the other side. Outside should be golden; inside slightly soft.

Serve immediately topped with warm homemade tomato sauce. Optional garnishes: orange slices, avocado slices, sliced green onions, fresh tomatoes.