Heat the vegetable oil in a large pan or wok over medium heat.
Add the red curry paste to the pan and stir-fry it for a minute or two until it becomes fragrant.
Pour in about half of the coconut milk and stir to combine with the curry paste. Cook for a few minutes until the mixture starts to thicken and oil begins to separate.
Add the sliced onions and bell peppers to the pan. Stir-fry for 2-3 minutes until they begin to soften.
Pour in the remaining coconut milk and bring the mixture to a gentle simmer.
Add the prawns to the pan and cook them until they turn pink and are cooked through, which usually takes 3-5 minutes.
Stir in the pineapple chunks and kaffir lime leaves (if using). Cook for an additional 2-3 minutes.
Season the curry with fish sauce and brown sugar to taste. Adjust the seasoning to your preference by adding more fish sauce for saltiness or more sugar for sweetness.
Remove the kaffir lime leaves if used and discard them.
10. Serve the red curry with prawn and pineapple over cooked jasmine rice.
11. Garnish with fresh basil leaves or cilantro.
Enjoy your flavorful Red Curry with Prawn and Pineapple! It's a delightful combination of sweet, spicy, and savory flavors.