Split open and quarter 1 loaf French bread. Mix 2 tablespoons each mayonnaise and dijon mustard and spread on the bread. Sandwich with sliced Swiss cheese, deli-style ham, roast pork, pickles and more cheese. Butter the sandwiches, then cook in a cast-iron skillet over medium-high heat, pressing with a heavy skillet, 2 minutes. Flip, reduce the heat to medium low and cook, pressing, until golden, 1 more minute.
Bring 3/4 cup water, 1/4 cup white vinegar, 3 tablespoons chopped onion, 1 tablespoon each salt and sugar, 1 teaspoon red pepper flakes and 3 minced garlic cloves to a boil; cook, stirring, 2 minutes. Pour over 1 sliced peeled large cucumber in a bowl and stir. Refrigerate 15 minutes.