Thai beef salad with chilli lime sauce

Ingredients

• 1 tbsp vegetable oil
• 300 g piece beef scotch fillet
• 250 g cherry tomatoes, halved
• 1 1/2 cups coriander leaves
• 1/2 cup mint leaves
• 1 Lebanese cucumber, halved lengthways, sliced
• 2 spring onions, thinly sliced
• 2 shallots, thinly sliced
• 8 kaffir lime leaves, thinly sliced
• 1 lemongrass stalk (white part only), thinly sliced
• 1 long red chilli, sliced
• Chilli dressing
• 2 small red chillies, seeded, finely chopped
• 1 garlic clove, crushed
• Juice of 1 lime
• 2 tbsp fish sauce
• 2 tbsp grated palm sugar