Slice onions thinly and layer in large saucepan. Add 1 tsp of salt to them and set aside to draw out the water for at least 30 minutes. Add 1/4 cup of oil and 1/2 cup water. Steam onions until transparent and water is cooked out. Meanwhile, place sliced bacon in a small amount of water in a shallow pan and blanch to remove excess fat. Bacon should be limp. Pour off liquid and coarsely chop. When water is cooked out of onions, add 1 tsp of flour and stir to dissolve. Remove from heat and add 2 egg yolks and Creme Fraiche, which has been mixed with the onions. Stir constantly. Spread onion mixture over the pastry and sprinkle wht chopped bacon on top. Bake at 500F for 10-15 minutes or until nicely browned. Cut into 1" squares for hors d'oeuvres. May be made a day ahead and reheated. Wait to cut until after heating if made ahead. May be baked in individual tartlet pans or a pie plate.