Preheat your oven to 375°F (190°C).
In a large skillet, heat the olive oil over medium heat. Add the diced onion, minced garlic, red bell pepper and jalapeño pepper. Sauté until the vegetables are softened, about 5 minutes.
Pour in the tomato sauce and let it simmer for a few minutes.
Add the chopped shrimp to the mixture and cook for about 3 minutes, or until they turn pink and are cooked through. Season with ground cumin, salt, and black pepper. Remove from heat and set aside.
In a separate saucepan, melt the butter over medium heat. Stir in the all- purpose flour to create a roux. Cook for about 1 minute, stirring constantly.
Gradually whisk in the vegetable broth until the mixture is smooth. Bring to a simmer and cook for 3 minutes, or until the sauce thickens.
Remove the saucepan from the heat and stir in the sour cream, green enchilada sauce, diced chilies, garlic powder, and half of the Monterey Jack cheese. Season with salt and pepper to taste.
Lightly grease the bottom of a 9×13” baking dish with olive oil.
Take a flour tortilla and spoon some of the shrimp filling onto the center. Roll it up tightly and place it seam side down in the baking dish. Repeat with the remaining tortillas and filling.
Pour cream sauce over the enchiladas. Sprinkle the remaining shredded Monterey Jack cheese on top.
Bake in the preheated oven for 15-20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let the enchiladas cool for a few minutes. Garnish with freshly chopped cilantro, sliced avocado, chopped red onion, lime wedges, and cheese.
Serve the shrimp enchiladas with pico de gallo.