Place beets in a small saucepan and add enough water to cover. Bring to a boil. Reduce heat and simmer, covered, 30 to 45 minutes or until very tender. Drain and cool, covered, until easy to handle. Peel skins from beets and chop.
In a medium bowl combine beets, yogurt, olive oil, tahini, onion, and garlic. Season with salt and pepper to taste. Cover and chill at least 1 hour.
Meanwhile, preheat oven to 375°F. Grease an8-inch baking pan. In a medium bowl whisk together eggs, fresh herbs, chile, cumin, coriander, turmeric, salt, black pepper, and baking powder; pour into prepared pan. Bake about 15 minutes or until set. Let cool at least 15 minutes.
To serve, cut frittata into rectangles. Serve frittata and beet salad in pita bread.