Preheat the oven to 190°C.
Cut the tomatoes in half, the onion into wedges, the carrots into 2cm chunks. Put these in a baking tray. Cut the beets in half - no need to peel them, if they’re organic.
Cut the bell peppers in half, remove & discard the seeds and stem, then cut the pepper flesh in half again and tuck between the tomatoes and onion together with the garlic. Drizzle with oil, dust with the dried herbs then season with salt and pepper. (You can add some balsamic or cider vinegar, lemon juice or white wine too),
Bake for about 30 minutes until the veggies are soft.
Let them cool in the tin, then remove the skins.
Put the veggies and the cooking jus in a blender and whiz until you get a textured sauce. Add the fresh herbs, some water or stock if it’s too thick and whiz again.
Transfer it to an airtight jar and keep refrigerated - or you can use it immediately. You can freeze it too, divided into smaller portions.