Place 4 chopped roma tomatoes and arbol chiles in a saucepan. Add water; bring to a boil. Reduce heat to medium; simmer for 1 minute. Remove from heat; cool to room temperature.
Transfer cooled tomatoes and chiles to a blender or food processor. Add 1/2 of the cooking water, 1/2 chopped onion, cilantro, 1 tablespoon oregano, 1 clove minced garlic, salt, and pepper. Pulse 6 to 8 times to chop ingredients. Transfer mixture to a bowl; stir in 1/2 of the shredded cabbage. Cover and refrigerate until serving.
Heat 1 tablespoon oil in a skillet over medium heat. Add 1/2 chopped onion; cook and stir until beginning to soften, 3 to 5 minutes. Stir in 2 cloves minced garlic and 2 diced tomatoes; cook 1 more minute. Add shrimp and 1 tablespoon oregano; cook and stir for 1 minute. Add 1/2 cup shredded cabbage, jalapeno pepper, salt, and ground black pepper. Cook and stir until shrimp turns opaque, about 3 minutes. Remove skillet from heat.
Heat oil in large saucepan to 350 degrees F (175 degrees C).
Place 3 tablespoons of the shrimp mixture in the center of each tortilla. Fold in half. Place filled tortillas in hot oil, working in batches if needed. Fry until golden brown, about 3 minutes. Turn carefully with tongs. Brown the other side, about 3 minutes more. Transfer cooked tacos to a paper-towel-lined plate to drain.
We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. Amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.
Per Serving: 554 calories;19.4 g fat;
62.9 g carbohydrates;
31 g protein;
173 mg cholesterol;
357 mg sodium.