Saute vegetables in 1 tablespoon butter. Set aside. Combine all ingredients except vegetables; beat at low speed of an electric mixer just until smooth. Stir in vegetables. Place well-greased muffin pans in a 425 degree oven for 3 minutes or until a drop of water sizzles when dropped in them. Remove pans from oven; fill half full with batter. Bake at 220ºC or 15 minutes. Reduce heat to 350 degrees, and bake an additional 18 to 20 NOTE: Popovers bake into crusty, hollow shells that you can eat alone or fill with sweet or savory sauces. Once in the oven, they'll rise high over the muffin pans. They're leavened by eggs and the steam created by the initial high oven temperature. Resist the temptation to open the oven door as they bake, or they won't rise as high. ----