To make the sauce, heat the oil in a saucepan and cook the onion for 5 minutes, or until softened and lightly browned. Add the ginger and garlic and fry for a few seconds more.
Add the curry powder, turmeric and star anise and season with salt and pepper. Cook for 1 minute. Sprinkle over the flour and stir well. Gradually add the stock, stirring constantly.
Add the tomato purée and sugar and bring to a simmer. Cook for 5 minutes, stirring occasionally. Remove from the heat and blend with a stick blender until smooth. (If you don’t have a stick blender, cool for a few minutes and blend in a food processor.)
Cut the tofu into six even slices. Spread the cornflour over a small plate and sprinkle the breadcrumbs over another plate. Dust one of the tofu slices lightly in cornflour, then brush with the yoghurt.
Turn the tofu in the breadcrumbs to coat on all sides, then transfer to a tray lined with baking paper. Repeat the process with the remaining tofu slices.
Pour the oil into a large frying pan and set over a medium heat. Using a palette knife, gently lower the tofu slices into the hot oil. Cook for 2–3 minutes on each side, or until the breadcrumbs are crisp and golden-brown. You may need to do this in batches. Drain the tofu on kitchen paper.
Meanwhile, warm the sauce, adding a little extra water if needed. Divide the rice between two shallow bowls or plates and top with the tofu. Pour over a little of the sauce and serve the rest separately.