STEP 1 In a large, wide pan, heat 1 tsp oil. Season the lamb well and fry until browned all over. Add the tikka paste to the pan for another 2 mins until fragrant. Add the onion and carrot with the remaining 1 tsp oil, and fry for 5 mins until the veg has softened. Tip into a large bowl and mix with the mint, chutney and frozen peas. Leave to cool.
STEP 2 Spread out a sheet of filo, with a short end towards you. Brush with oil all over. Fold each long edge into the centre by 5cm, so you have a long, narrow piece of filo. Add about 130g of mixture to the top left of the strip and fold the top right corner of filo over to make a triangle. Continue folding down the length of the pastry to make a samosa shape. Brush with more oil. Transfer to a baking tray lined with baking parchment, wrap in cling film and freeze. Use within 3 months.
STEP 3 To cook from frozen, heat oven to 200C/180C fan/gas 6. Cook the samosas on their baking tray in the middle of the oven for 35-40 mins, turning over halfway through cooking, until golden and piping hot in the middle. Drain on kitchen paper to absorb excess oil and serve with salad, the extra chutney and raita.