Pressed Picnic Sandwich with Roasted Red Pepper and Pepperoncini Spread

½ cup mayonnaise

⅓ cup roasted red peppers, finely chopped

1 tablespoon fresh lemon juice

2-3 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

¼ pound prosciutto, thinly sliced

¼ pound salami, thinly sliced

1 cup marinated artichoke hearts, drained and sliced

2 cup loosely packed arugula

Balsamic vinegar, as needed

Kosher salt and freshly cracked black pepper