Wash and peel the carrots and cut them into 7 cm sticks. Slice the green chillies lengthways and put both into a bowl with the lemon juice, turmeric, salt and split mustard seeds. Toss together well.
In a small frying pan, heat the oil for a few minutes and then add the black mustard seeds. Let them fizzle and pop and then pour them over the carrot mixture. Toss together well and serve.