1lb 2 oz/500 g lean beef tenderloin

2 tbsp vegetable oil

1 garlic clove, chopped finely

1 lemon grass stem, shredded finely

1 inch/2.5 cm piece fresh ginger root, chopped finely

1 red bell pepper, deseeded and sliced thickly

1 green bell pepper, deseeded and sliced thickly

1 onion, sliced thickly

2 tbsp lime juice

Boiled noodles or rice, to serve

Cut the beef into long, thin strips, cutting across the grain.   Heat the oil in a large skillet or wok over a high heat.  Add the garlic and stir-fry for 1 minute. 

Add the beef and stir-fry for another 2-3 minutes, or until lightly coloured.  Stir in the lemon grass and ginger, and remove the wok from the heat. 

Remove the beef from the skillet or wok, and keep to one side.  Add the bell peppers and onion to the skillet or wok, and stir-fry over a high heat for 2-3 minutes, or until the onions just turn golden brown and are slightly softened.  Return the beef to the skillet, stir in the lime juice, and season to taste with salt and pepper.  Serve with noodles or rice.