Beetroot veggie burgers

Name: Beetroot veggie burgers
Ingredients: 3 tbsp olive oil; 1 red onion, finely chopped; 2 garlic cloves, crushed; 2 raw beetroots, peeled and grated; 1 courgette, grated; 2 large carrots, peeled and grated; 100g/3½oz porridge oats; 400g tin chickpeas, drained; 3 tbsp tahini; 1 large free-range egg yolk; 4 spring onions, thinly sliced; 3 tbsp finely chopped fresh coriander; sea salt and freshly ground black pepper; extra virgin olive oil, for drizzling; 2 large sweet potatoes, peeled and cut into 1cm/½in-thick rounds; 200g/7oz halloumi, cut into 1cm/½in-thick slices; 3 large garlic cloves, thinly sliced; 2 red chillies, thinly sliced; 6 handfuls mixed salad leaves; 2 cooked beetroots, cut into 1cm/½in cubes; handful fresh basil, finely chopped; 1 garlic clove, crushed; 1 lime, juice only; 3 tbsp extra virgin olive oil; 6 wholewheat sourdough buns, halved; 230g/8oz hummus; 2 avocados, sliced; ½ red cabbage, shredded