Fill a large pot with water and add the ginger slices and spring onion. Bring the water to a rolling boil.
Carefully add the prawns and cook over high heat for 1–2 minutes, or until they turn red and curl up. Immediately remove them from the hot water to prevent overcooking, as overcooked prawns become rubbery. Let them cool completely.
Cut the cucumbers into large chunks. Using the flat side of the knife, smash each piece until it cracks apart. This technique creates rough, uneven edges that absorb the dressing much better than neatly sliced cucumbers, giving every bite more flavour.
In a mixing bowl, combine the soy sauce, oyster sauce, brown sugar, chopped bird's eye chilies, chili powder, chili flakes, and minced garlic.
Heat the cooking oil until hot, then carefully pour it over the garlic and spices. Stir well until the sugar dissolves and everything is well combined.
In a large serving bowl, combine the cooked prawns, smashed cucumbers, red onion, cilantro, lemon slices, and the pulp from the passion fruits.
Pour the dressing over the salad and gently toss until everything is evenly coated.
You can enjoy the salad immediately, but for the best flavour, refrigerate it for about 20 minutes. Chilling allows the prawns to absorb the dressing while making the salad extra refreshing.
Serve cold as an appetizer or alongside steamed rice.
