ROASTED SWEET POTATO AND GOATS' CHEESE SALAD

500g (about 2 medium to large) essential Waitrose Sweet Potatoes • 1 tbsp olive oil • 50g pecan halves • 2 tbsp extra virgin olive oil • 1 small red onion, finely sliced • 130g tub pitted black olives, drained and roughly chopped • 1½ tbsp balsamic vinegar • 250g pack pre-cooked • red and white quinoa • 115g bag baby spinach • 125g soft goats’ cheese, crumbled • Squeeze lemon juice