Cheesy Potato Waffles

Brunch just got a little more blissful.

800g potatoes 1 cup finely grated halloumi ½ cup finely grated parmesan 3 spring onions 2 cloves garlic 1 whole egg 2 Tbsp fine white wheat flour flaky salt and freshly ground black pepper 1 red onion 3 Tbsp apple cider vinegar 2 tsp sugar pinch of salt 1½ cups plain yoghurt grated zest of 1 lemon 200g smoked trout ribbons capers soft herbs lemon wedges