Heat oil in a deep pan. Sauté onions and garlic.
Add beef cubes and cook until color changes.
Add vinegar, salt, pepper and cook over moderate heat until sauce is reduced to its original amount. Do not stir until mixture boils.
Add water and cook covered until beef is tender.
Add coconut milk and finger pepper and let it simmer for 10 minutes over low heat.
Happy cooking, Foodies!