Beetroot rosti with green yogurt smoked salmon

Name: Beetroot rosti with green yogurt & smoked salmon
Ingredients: 600g beetroot, trimmed, peeled and coarsely grated; 400g potatoes, coarsely grated; 2 tbsp olive oil; 1 red onion, finely sliced; 5 large eggs; 4 tbsp flour; 2 tbsp butter; 1 tbsp white wine vinegar; 200g smoked salmon; 170g Greek yogurt; ½ bunch of dill, plus extra to serve; ½ bunch of parsley; pinch of ground cumin; 1 tbsp capers, drained and rinsed