Using a pestle and mortar or food processor, pound or blitz the chillies and garlic to a paste.
Heat the oil in a wok set over a medium heat and fry the chillies and garlic paste until golden brown.
Add the beef and stir in the fish sauce, light soy sauce, sugar and oyster sauce. Toss to mix well, then stir-fry for roughly 1-2 minutes until the meat is cooked.
Add the red/green chillies and long beans, cook for 30 seconds, then mix in the basil and lime leaves.
Remove from the heat and serve at once with steamed rice, topped with a slightly runny fried egg.