Bring a pot of salted water to a boil. Then, cook all the vegetables for 5 minutes. 

Drain the vegetables and cool in a colander for at least ten minutes. Wring out the remaining water with a towel or your hands.

Transfer the cooked vegetables to a bowl and add the scallions. In another bowl, combine the flour, salt and pepper, baking powder, and thyme. Add to vegetable mixture and stir. Add egg and stir. 

In a big skillet, heat 1-2 tablespoons of olive oil over medium high heat. Drop a 1/4 cup of the mixture into the skillet. Flatten with your spatula. Cook for 4-5 minutes on each side, or until golden brown. Drain on paper towels.

Serve with a big spoonful of the yogurt topping.