Drain and rinse the jackfruit and pat it dry with a clean towel. Make sure to dry as much water as possible so that the salad isn't soggy. Add the jackfruit to a large bowl and use a potato masher to mash the jackfruit until it is broken up and looks shredded. Sometimes jackfruit can be quite tender while sometimes it can be tougher, so if you have a tougher jackfruit it might take a bit of strength mash. If you prefer you can first chop the jackfruit as directed in this post before mashing it to make it a bit easier to mash.
Add all of the remaining jackfruit salad ingredients to the bowl along with the mashed jackfruit and stir well to combine.
To make vegan jackfruit salad sandwiches: toast the bread if desired. Layer 4 slices of bread with a lettuce leaf (if using) and then follow with a generous serving of the vegan jackfruit salad. Top with the remaining slices of bread and serve.
Oil-free: to make oil-free, sub my vegan sour cream from Fuss-Free Vegan or store-bought vegan yogurt for the mayonnaise. Other uses: this jackfruit salad is great on a sandwich, but it's also delicious served with crackers as a kind of dip, or on lettuce leaves to make lettuce wraps. Make ahead: The jackfruit salad sandwich mixture tastes even better the next day making it the perfect make-ahead meal. Store prepared jackfruit salad in an air-tight container in the fridge for up to 5 days. Make the sandwiches fresh.