Preheat the oven to 220°C, fan 200°C, gas 7. Make 3mm slits in the beetroot, stopping 1cm from the bottom to keep them together. To do this, simply place the beetroot between two wooden spoon handles and cut down until the knife reaches the handles.
Place on a baking dish, sprinkle with 3 tbsp oil, and season with salt and pepper. Roast for 1 hour, rotating the tray midway through to ensure they don't stick, until the vegetables are soft and crisp.
Meanwhile, whizz the parsley, coriander, basil, chili, lemon juice, garlic, and 2 tbsp oil in a food processor to produce the dressing. If it's too thick, add a splash of cold water.
Arrange the beetroot on top of the yogurt on a serving plate. Drizzle the herby dressing over the salad and sprinkle with lemon zest and a pinch of black pepper.