1. Preheat the oven to 180°C. Place the tofu, pepper, red onion and thyme onto a baking tray, drizzle with olive oil and balsamic vinegar.
2. Cover with tin foil and bake for 20 minutes. Remove the foil and bake uncovered for a further 15 minutes .
3. While the tofu bakes, place the buckwheat, herbs and rocket into a bowl. Add a drizzle of olive oil, lemon zest and a pinch of salt. Toss lightly to coat.
4. Once the onions have softened and are becoming crisp on the edges, remove from the oven and allow to cool slightly or completely before serving with the herbed buckwheat.