Combine all of the sauce ingredients in a food processor or blender. Process until smooth.
Scrape the sauce into a small bowl, cover and set aside until ready to serve.
TACOS
Heat the olive oil in a large skillet over medium high heat. Add the garlic, bell peppers and onion, and stir fry until slightly softened, 3 to 4 minutes. Add the shrimp, and continue to stir fry until the shrimp are pink and curled up (cooked through), 4 to 5 additional minutes. Sprinkle in salt and pepper, to taste. Remove the skillet from heat.
Fill each tortilla with shrimp, peppers and onions, plus ¼ cup lettuce and a generous spoonful of the chimichurri sauce.
Notes
If you are preparing this recipe as gluten free, just be sure to use a brand of corn tortillas that are known to be GF.