Beetroot feta asparagus salad

Name: Beetroot, feta & asparagus salad
Ingredients: a large handful of fresh oregano or marjoram leaves; 1 garlic clove; juice of 1½ lemons; 4 tbsp extra-virgin olive oil; 250g bunch asparagus, cut into 3cm/1¼in lengths; 2 x 250g packs boiled fresh beetroot, cut into quarters; zest of 1 lemon; 2 spring onions, finely sliced; 85g bag watercress, large stalks removed; 10 green and 10 purple basil leaves (or 20 of one colour); 400g feta or goat's cheese