Cook the quinoa according to the packet instructions. Rinse and drain, then set aside.
Meanwhile, put the beans in a pan of cold water. Bring to the boil. Cook for one minute, then turn off the heat. Drain the beans and rinse them in cold water (ideally keep them in a bowl of icy water for 5 minutes, then drain).
Peel the lemon and remove the white membrane. Cut the flesh into small chunks and put them into a large serving bowl. Squeeze over the juice.
Peel the avocado, remove the stone, then slice the flesh thinly. Add these to the lemon and combine gently.
Cut the radishes in half, add these to the avocado.
Add the drained beans to the avocado together with the quinoa, radish sprouts, chilli flakes, cumin, garlic and olive oil - then gently combine the salad. Taste, then season with salt and pepper to your liking.