Hull and dice the strawberries into small, bite-sized pieces. Peel, core, and dice the pineapple into similar-sized pieces. Add both to a large mixing bowl.
Finely chop the red onion and add to the bowl.
If using jalapeño, remove ribs and seeds, then finely mince. Add to the bowl.
Chop the fresh cilantro and add to the bowl.
Zest half a lime directly into the bowl, then squeeze the juice from the full lime over the mixture.
Add a pinch of salt.
Gently stir everything together until evenly combined. Be careful not to crush the fruit.
Cover and refrigerate for at least 30 minutes to allow the flavors to meld.
Serve with tortilla chips or as a topping for grilled chicken, salmon, shrimp, or fish tacos. Optionally, serve in a hollowed-out pineapple half for a stunning presentation.