Grind the black peppercorns in a mortar until fine. Add the sliced turmeric and grind into a fine paste. Next, add the red curry paste and shrimp paste, pounding to combine everything nicely.

Heat your wok over medium heat and add the neutral oil. Once hot, add the prepared curry paste and sauté for about 2 minutes until aromatic.

Add the palm sugar, stirring until it dissolves. If the mixture looks too dry, add a small splash of water.

Add the drained tuna to the wok, stirring gently until well-coated. Cook until the mixture becomes dry and crumbly—about 4-5 minutes.

Stir in the sliced lemongrass, julienned lime leaves, and optional chilies. Turn off the heat, taste, and add fish sauce as needed. Toss in cilantro just before serving.