In a saucepan cover eggs with cold water by 1 inch and bring to a boil. Remove pan from heat and let eggs stand, covered, 7 minutes if using quail eggs or 17 minutes if using large eggs. Peel and halve eggs. Cut bacon into 1-inch pieces. In a large heavy skillet cook bacon over moderate heat until crisp and golden and transfer to paper towels to drain. Quarter and seed tomatoes and cut into 1/4-inch-thick slices. Thinly slice scallions, radicchio, and romaine separately. Halve, pit, and peel avocado. Cut avocado into 1/2-inch pieces. Cut chicken crosswise into 1/4-inch-thick slices and crumble cheese. In a large bowl toss together all ingredients and season with salt and pepper. *Available at specialty foods shops and many supermarkets.