1. Cook the quinoa according to the package instructions. Drain and let cool.
2. Sauté the minced onion and minced garlic in a little olive oil. Add the spinach and cook until wilted. Let cool.
3. In a bowl, mix together the cooked quinoa, wilted spinach, crumbled feta, eggs, flour, salt, and pepper.
4. Shape the mixture into small patties using your hands or a cookie cutter.
5. Heat a drizzle of olive oil in a skillet. Cook the patties for 3 to 4 minutes on each side until golden brown.
6. Prepare the sauce by mixing together yogurt, lemon juice, olive oil, mint, salt, and pepper.
7. Serve the patties hot or warm with the sauce.