Peel the shrimp and remove the tails.
Layer the raw shrimp at the bottom of the slow cooker.
Drizzle with 1 tablespoon olive oil, then mix in the chopped onion.
Drain the canned, fire-roasted tomatoes, and pour it over the shrimp. Stir together.
Add the bell pepper and the rest of the ingredients, including seasonings and cilantro. Stir all together. Cook on LOW for 2–3 hours.
Check on the shrimp around 2 hours of cooking. If they look almost done, cook for another 30 minutes to an hour. They should be seasoned nicely and pink, similar to that of steamed shrimp.
Serve with Bibb lettuce leaves or keto tortillas.
Top with a selection of your favorite toppings such as extra cilantro, chopped purple cabbage, chopped green onion, coconut yogurt, avocado, jalapeño pepper, or pickled onions and carrots.