I roasted a batch of beetroot because I think this is the best way to retain flavour and colour. Put the whole beetroot onto a baking tray and cover with foil, bake in an oven at 150C for about 2 hours until soft (poke with a fork), leave to cool and remove the skin, chop roughly. You can use bought vacuum packed cooked beetroot if you wish.
Preheat your oven to 180C.
Fry the onion gently in the oil until soft.
Add the garlic, cumin seeds and chipotle flakes and fry for a further minute until aromatic.
Place the cooked beetroot, onion mixture, tahini, drained chickpeas and lemon juice into a blender and pulse until you have a firm paste, add water if needed. You can mash it all with a potato masher or a fork if you don't have a blender.
Turn the falafel mixture out into a bowl. Take a spoonful of the mixture and roll it into a ball (if your mixture is too sticky stir in a little flour but don't be heavy handed - you want moist falafel to eat!), squash it a bit to form a patty and place on a greased baking tray.
Repeat with the remaining mixture until you have 16 falafel.
Bake in the preheated oven for 15 minutes, turning with a spatula once - they should be firm on top and just beginning to brown.