Add the tomatoes to the bowl of a food processor and plus to chop, leaving some large pieces. Transfer to a large serving bowl. Add the onions and garlic and pulse to chop. Add to the tomatoes. Stir in vinegar, monk fruit, and hot sauce. Season with salt, about 1 1/2 teaspoons. Refrigerate sauce until ready to serve. To serve, add shrimp, avocado, cucumber, and cilantro and stir to combine.