Make the tacos: Place chicken breasts and salt into a pot and cover halfway with water. Bring to a boil; cook until an instant-read thermometer inserted into the center reads at least 165 degrees F (74 degrees C), about 15 minutes. Remove from the pot and cool until easily handled, about 5 minutes. Shred into thin pieces.
Heat 1 tablespoon vegetable oil in a large skillet over medium heat. Add onion, tomato, and bell pepper; cook and stir until softened, about 2 minutes. Stir in shredded chicken, bouillon granules, and black pepper; cook until golden brown, about 5 minutes.
Spoon some chicken mixture into the middle of each corn tortilla. Fold tortillas around the filling and secure with a toothpick.
Heat oil in a deep-fryer or large saucepan to 350 degrees F (175 degrees C). Fry tortillas in batches until golden and crispy, about 2 minutes per side. Drain on paper towels.
Make the sauce: Bring water to a boil in a small saucepan. Add tomato sauce, bouillon granules, and seasoned salt. Cook and stir over medium-high heat until sauce thickens, about 5 minutes. Serve sauce over tacos.