Start with the potato stars. Cut the regular and sweet potatoes into thick (1cm) slices. Use a small and a medium metal star cutter (approx.3cm and 5cm across) to cut small stars from the slices. Place the sliced stars onto a baking tray. Drizzle on the oil, then sprinkle on the paprika, salt and pepper. Toss together, so the potatoes are evenly covered. Place in the oven to cook for 20-25 minutes, turning once, until the potatoes are golden.
Whilst the stars are cooking, make the lentil and mushroom bowl. Heat the olive oil in a large saucepan and add the onions. Cook on a medium heat, stirring regularly until the onions start to soften (about 5 minutes). Add in the garlic, salt, black pepper, white pepper and cumin, stir together and heat for 1 minute.
Add in the lentils and mushrooms. Stir again, then pour in the stock, balsamic vinegar, brown sugar and tomato puree. Bring to the boil, then simmer gently for 20 minutes, stirring occasionally. After 20 minutes, stir through the cream. If you’d like the sauce to be thicker, mix the cornflour with 3 tbsp cold water, and stir through the mixture. Stir in the spinach, and cook for 2-3 minutes, until the spinach wilts.
Meanwhile, make the red onion gravy. Heat the olive oil and margarine until the margarine melts. Add the red onions and brown sugar. Cook over a medium heat, stirring occasionally for 15 minutes, until the onions soften and start to caramelise. Add the salt, pepper and garlic. Cook for a further 2 minutes, then stir through the flour using a whisk.
With the heat on medium-high, slowly pour in the stock, a splash at a time. Stir with the whisk each time to remove any lumps. Continue until all the stock is used and the gravy has thickened. Add half the balsamic vinegar. Taste, season with more salt and pepper and the remaining balsamic vinegar if needed. Keep warm until ready to serve.
Once the lentils and mushrooms are ready, spoon into four bowls. Top with the potato stars and a sprinkling of fresh herbs. Serve with the onion gravy.