Curried red lentil soup

Name: Curried red lentil soup
Ingredients: 1 tbsp coconut or olive oil; 1 large onion, chopped; 2 garlic cloves, crushed; 30g/1oz fresh root ginger, peeled and grated; 1 red Scotch bonnet chilli (or a milder red chilli if you prefer), seeds removed and finely chopped; 2 tsp garam masala or curry powder; 25g/1oz tomato purée; 1 x 400g tin reduced-fat coconut milk; 150g/5½oz red split lentils; 2 sweet potatoes, scrubbed and cut into 2cm/¾in cubes; 1 red pepper, seeds removed and cut into 2cm/¾in chunks; 200g/7oz baby leaf spinach; pinch salt