Prepare all ingredients, ensuring the pork is sliced thinly for quick cooking.

Heat the vegetable oil in a large wok or deep skillet over medium heat.

Add the curry paste to the hot oil and stir-fry for about 2 minutes until it becomes fragrant and slightly darker.

Pour in about 1/3 of the coconut milk. Stir constantly until the oil starts to separate from the curry mixture.

Add the sliced pork to the pan and stir to coat it in the curry sauce. Cook for 3-4 minutes until the pork is no longer pink on the outside.

Pour in the remaining coconut milk, fish sauce, and brown sugar. Stir well to combine.

Add the sliced red bell pepper and bring the mixture to a gentle simmer. Cook for 5 minutes until the peppers are tender-crisp and the sauce has thickened slightly.

Stir in half of the crushed peanuts and the sliced kaffir lime leaves (if using).

Taste the sauce and adjust with a splash more fish sauce for saltiness or sugar for sweetness if desired.

Serve hot over steamed jasmine rice, garnished with fresh cilantro and the remaining crushed peanuts.