Start this recipe by cooking the quinoa in boiling water for approximately 12-15 minutes. Drain and put aside. Meanwhile, heat the oil in a pan and sauté the onion, garlic and chilli till soft. Place the drained black beans into a large bowl and mash with a fork. Add in the cooked onion mixture followed by the cooked quinoa, ground cumin, chopped coriander and season well with salt and pepper. Add in the beef mince substitute, beaten egg and breadcrumbs and mix together well. Form into 4 large burgers and place onto a lined baking tray. Brush with a little olive oil and bake in the oven for 15-20 minutes. You can also place the curly fries onto a baking sheet and bake for 20 minutes. Heat the remaining tbsp olive oil in a pan and fry the sliced onions for 10 minutes to caramelize. To put the burgers together, cut the burger buns in half. Spread both sides with a little mayonnaise. Place a few salad leaves on the 4 bun bottoms and place a vegetable burger onto each. Cover with the sliced tomato, caramelized sliced onions and finish off with the crumbled feta cheese on top. Serve with the curly fries on the side.