30 MINUTES OR LESS. Dagwood Bumstead of the Blondie comic strip loves his mile-high sandwiches with layers and layers of lettuce, cheeses and deli meats. This vegetarian take on the comic classic is shorter but with a plentiful filling. Use a bread of substance, such as a sourdough, and be sure to use slices from the center of the loaf so the slices are of uniform size. Offer this sandwich at a casual get-together and, of course, use whichever combinations and in whatever amounts of ingredients you wish this recipe is only a suggestion. In fact, you can come up with other ingredients, and that would work as well. Possible accompaniments include tomato soup and all-American ice cream sundaes.