Pressed Picnic Sandwich with Roasted Red Pepper and Pepperoncini Spread

Name: Pressed Picnic Sandwich with Roasted Red Pepper and Pepperoncini Spread
Ingredients: 1/2 cup mayonnaise; 1/3 cup roasted red peppers, finely chopped; 1 tablespoon fresh lemon juice; 2 to 3 pepperoncini, finely chopped; 1 clove garlic, grated; Kosher salt and freshly cracked black pepper; 1(12 to 14-inch) loaf ciabatta bread, sliced in half lengthwise; 5 ounces herbed goat cheese; 1/4 pound prosciutto, thinly sliced; 1/4 pound salami, thinly sliced; 1 cup marinated artichoke hearts, drained and sliced; 2 cup loosely packed arugula; Balsamic vinegar, as needed