If tomatoes are in season, swap canned tomatoes for freshly chopped tomatoes with their juices.
In a pinch, V8 juice, tomato juice, or Clamato juice can substitute for the ketchup, but ketchup is the standard ingredient.
Ingredients:
1 pound medium shrimp, raw or cooked
Kosher salt
1 cup chopped red onion
1 cup peeled, diced cucumber
1/2 cup chopped celery
1 jalapeno, minced
1 (15-ounce) can whole peeled tomatoes, chopped OR 1 1/2 cups chopped fresh tomatoes
1/2 cup ketchup
1/4 cup chopped cilantro
2 tablespoons lime juice
1 to 4 tablespoons hot sauce, such Crystal or Tabasco, to taste