In a large pot, heat olive oil and cook onion for 3-4 minutes until softened. Add garlic and cook for another minute.
Add cumin, mustard seeds, curry powder and continue to cook for another minute until fragrant.
To the pot, add the Superblend Fibre mix, sweet potato, vegetable stock, canned tomatoes, salt, and chilli flakes. Bring to the boil, then cover and simmer for 20 minutes until the lentils and sweet potatoes are just tender. Remove lid and simmer gently for a further 5 minutes to reduce the sauce. Stir through a handful of spinach leaves and season to taste.
Divide curry into 4 bowls, dollop with yoghurt, top with more spinach leaves, coriander, sliced fresh chilli and serve.