Wash salmon and par dry. Boil, grill, or barbecue until thoroughly cooked and meat begins to flake. Remove from heat and set aside.
To make sauce, in a microwave-safe 1 quart bowl or a small sauce pan, mix together water,tomato paste, oil, chili powder, cayenne, oregano, chilies, garlic, cumin, and onions, If micrwaving, cover and microwave on HIGH for 30 seconds; if cooking on a stove top, put heat on medium and heat, stirring for 3 minutes, or until onion has begunto soften. Remove from heat handset aside.
Preheat oven to 350 degrees. Spoon several tablespoons of sauce into an oven-proof baking pan.
Individually dip tortillas into the sauce and place in the oven pan.
Fill each tortilla with one quarter of the salmon and 1 tablespoon of shredded cheese. Fold tortillas over.
Bake for 10 minutes. or until bubbly. Remove from the oven. Top with sour cream and serve.