Peel and chop up your beets and onions and spread them out on the lined baking sheet with the garlic and rosemary. Drizzle a bit of olive oil over them and sprinkle some crushed black pepper.
Toss well and follow it up with a sprinkle of salt. Mix well again.
Pop this in the oven and bake for 35-60 minutes, or until the veggies are golden brown and caramelized.
Allow these to cool down, transfer to a blender jar and blend until you get a smooth paste.
Notes
Chop up the beets into equal sized chunks to ensure even cooking. This is important, regardless of whether you're roasting, pressure cooking or boiling the beets.
Make sure you toss them in olive oil before you roast them. This gets them nice and crispy and offers a beautiful caramelization too.
To adjust the texture and consistency of the puree, start with less water while blitzing it, and add more if needed.