Bring water to a boil. Add 1/2 tsp salt and 1 tsp olive oil, if desired. Stir in quinoa. Cover with lid; reduce the heat to low and simmer 15 minutes. Remove from heat and let stand (covered) for 5 minutes. Fluff with a fork and let it cool.
Make the yogurt sauce by mixing together all the ingredients.
In a bowl, mix together the cooked quinoa, sweet potato, zucchini, green onions, Parmesan cheese, breadcrumbs, eggs and the seasoning. Take a handful of the mixture and shape it into a patty.
In a skillet, heat some olive oil over medium-high heat. Carefully place the quinoa patties in the pan and cook them on each side until they are golden brown and crispy. Serve them with a dollop of yogurt sauce.
