Heat oven to 200°C/gas mark 6.
Cut the carrot into 1 inch chunks and then cut each piece lengthwise into small sticks.
Put the carrot in a small roasting tin and toss with the cumin or curry powder and 1tbsp olive oil. Roast for about 30 minutes, turning halfway through.
Cut the onion into fine slices and fry in 1 tbsp olive oil until soft.
Add the lentils and cook to heat through.
Mix in the roast carrots and lemon juice.
Transfer to a serving dish and crumble the feta over the top.