Finely chop the lemongrass, slice the chili peppers and green onions, and set aside. Heat a pan with just a little oil, and fry the fish on both sides until golden. Remove and set aside.

In the same pan, sauté the green onions, chili peppers, and lemongrass until fragrant. Add the sugar, tamarind paste, and chili oil. Add a little water, season to taste, then return the fish to the pan and toss gently to coat the fish with the sauce.

Finally, add the green onions and turn off the heat. This dish is sweet and tangy. Serve hot with boiled vegetables.