Blend the onion, garlic, ginger, chilli and dried shrimp in a food processor until it forms a smooth paste.
Heat the oil in a wok over a medium heat and cook the paste, stirring constantly, for about 2 minutes, until the oil separates from the other ingredients.
Add the beef and stir-fry until the meat becomes opaque, then add the tamarind paste, soy sauce and water. Simmer, uncovered, for 2–3 minutes, until most of the liquid has evaporated and the meat is tender. Stir in the sugar and shredded mint leaves, season to taste and garnish with chives and a few whole mint leaves. Serve with a vegetable dish and rice, if liked.