Beetroot Feta Grain Salad

• 200 g whole beetroots, cooked and quartered
• 1 red onion, thinly sliced
• .5 cup quinoa
• .5 cup parsley, roughly chopped
• .5 cup mint, roughly chopped
• 1 cup peas, frozen
• .25 cup walnuts, toasted and crushed
• 1 tbsp olive oil
• 1 tbsp lemon
• 100 g Danish feta