Rinse the lentils really well in two changes of water, then leave to drain in a sieve.
Heat 1 tsp oil in a large pan and fry the onion and carrot with a pinch of salt for 5 minutes, until soft, then add the garlic, half the thyme and the bay leaf. Fry for a minute then stir through the lentils.
Add the veg stock, season, and simmer for 40-50 minutes until the lentils are tender and creamy. Top up with water if they start to stick to the bottom of the pan.
Stir through the remaining thyme, spinach and coconut milk and simmer until the spinach wilts then season again if it needs it and stir through the lemon juice, to serve.