Heat 1 tablespoon vegetable oil in a Dutch oven or large wide pot over medium-high heat. Add the shrimp, 1 teaspoon chili powder and 1/4 teaspoon salt. Cook, stirring occasionally, until the shrimp are just cooked through, about 3 minutes; transfer to a bowl.
Add the remaining 3 tablespoons vegetable oil and the pasta to the pot. Cook, stirring, until golden, 3 minutes; transfer to a separate bowl.
Reduce the heat to medium and add the onion, bell pepper, 1/2 teaspoon salt and 1 to 2 tablespoons water to the pot. Cook, stirring, until the vegetables soften, about 3 minutes.
Increase the heat to medium high; stir in 2 cups water, the tomatoes, toasted noodles and 1/2 teaspoon salt. Bring to a simmer, stirring to break up any clumps. Cover, reduce the heat to medium, and cook, stirring occasionally, until the noodles are tender and most of the water is absorbed, 10 to 12 minutes. Stir in the shrimp. Top each serving with sour cream, pickled jalapenos and cilantro.