I like to prepare all of the accompanying components before I make the burgers. Heat a small saute pan over medium heat. Add a few teaspoons of olive oil and saute the onions until they are caramelized, or for about 10 minutes. You can make the yogurt sauce and toast the buns while the onions are caramelizing.
Make the sour cream and yogurt sauce by combining those ingredients with the dill, garlic, sumac, lemon zest and juice. Season to taste with salt and pepper, cover, and set aside in the refrigerator until you are ready to serve the sliders.
Make the burgers by combining the first nine ingredients in a large bowl (ground turkey - salt and pepper). Mix with your hands until all of the ingredients are blended evenly throughout. Make the mixture into 8 sliders that are 3-4 oz each. Place them on a cookie sheet that is lined with saran wrap as you finish making them. Gently press into small patties.
Heat a large saute pan over medium heat. Add a light drizzle of vegetable oil or spray the pan with cooking spray. Add the sliders to the pan and cook for 6 minutes per side, covering the pan as they cook. They sliders will be firm to the touch when they are cooked through.
Assemble the sliders by laying all of the bottom buns on a serving tray. Add a few pieces of the mixed greens to the bottom, and place the sliders on top. Add a scant tablespoon of red onion to each burger. Slather the yogurt sauce onto the tops of each of the buns before assembling. Serve hot to room temperature.
Recipe by Cooking in Red Socks at http://www.cookinginredsocks.com/2014/02/25/turkey-and-zucchini-sliders/