300g mini Portobello mushrooms or chestnut mushrooms, sliced
2 garlic cloves, crushed
1 ½ tsp ground cumin
1 tsp smoked paprika
2 x 400g cans green lentils, drained and rinsed (drained weight 240g)
1 tbsp soy sauce
1 tbsp balsamic vinegar
1 medium sweet potato, peeled and very thinly sliced
1 large potato, very thinly sliced
1 thyme sprig, leaves picked
Heat oven to 200C/180C fan/gas 6. Heat half the oil in a medium saucepan. Fry the onion for 3 mins, then add the mushrooms. Cook for another 3 mins, then increase the heat and add the garlic, ground cumin and paprika, and cook for 1 min. Remove from the heat and add the lentils, soy sauce, balsamic vinegar and 100ml water. Season, then tip the mixture into a casserole dish.
Rinse the saucepan and return to the hob. Add a kettle full of boiled water and bring back to the boil over a high heat. Add the potato slices, cook for 3 mins, then drain. Arrange on top of the lentils, then brush with the remaining oil. Roast in the oven for 25 mins until the potatoes are golden, then scatter over the thyme before serving.