Bring water to the boil in a saucepan. Add quinoa and bring back to the boil. Reduce heat and cover; simmer until tender, about 20 minutes. Pour into a sieve; run cold water over quinoa to cool slightly.
Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to the boil. Add sweet potato and beetroot; cover and steam until tender, about 15 minutes. Add edamame; steam until tender, about 5 minutes. Drain and cool until running water.
Combine tomato, red pepper, spinach, red onion, balsamic vinegar, olive oil, lemon juice, garlic and black pepper in a large bowl. Fold in cooked quinoa, sweet potato, beetroot and edamame beans. Top salad with goat cheese.