1. Preheat oven to 375°F.
2. Slice cucumbers and tomatoes and set aside.
3. Mash sweet potatoes and mix in the quinoa , oatmeal, 1/2 beaten egg, feta, onions, garlic, chipotle powder and spinach, adding salt & pepper to taste. Refrigerate mixture for 15 minutes.
4. Form the chilled mixture into four burger patties.
5. Add 2 tbsp. canola oil to a skillet or grill pan and heat to medium-high.
6. Add patties (2 at a time) and cook 3 minutes per side; finish baking patties in the oven for 8 minutes.
7. Once the patties are fully cooked, grill the buns and top them with tzatziki, lettuce, a quinoa patty, Havarti cheese, and cucumber.