Chop the beetroot (you may want to use gloves), pepper (deseeded), carrots, onion and mushroom.
Add the beetroot, pepper, and carrots into a pan, cover with water and simmer until the beetroot is cooked (10–15minutes). Drain and set the water to one side (used later on).
Heat the oil in a heavy non-stick pan and sauté the onions and mushrooms. Reduce to a low heat, add the rice and stir to stop the rice sticking and ensure that all the rice is covered with oil and onions.
Add 250ml of the stock and stir until it is absorbed. Add some of the set-aside water and more stock and simmer for 15 minutes.
Add the peas and simmer for a further 15 minutes. Season to taste.
Combine the beetroot mixture and stir through, allowing the beetroot to colour the rice.
Serve, garnishing with feta cheese and fresh mint.