Ingredients

1 head garlic 

Coarse salt 

Extra-virgin olive oil 

1 red onion, halved lengthwise 

2 teaspoons Dijon mustard 

1/2 cup mayonnaise 

4 submarine rolls (10 to 12 inches long), cut in half horizontally 

20 to 24 thin slices roast pork

Roasted fennel, chiles, and pitted olives (optional)

16 thin slices provolone or fontina cheese 

Preparation

Preheat oven to 375 degrees. Cut off and discard top 1/2 inch of garlic head. Season garlic with salt, drizzle with oil, and wrap snugly in foil. Roast until tender when squeezed, 50 to 55 minutes.

Meanwhile, toss onion with just enough oil to coat, and roast on a rimmed baking sheet 40 to 45 minutes.

When garlic is cool enough to handle, squeeze from skin; lightly mash with a fork. Stir in mustard and mayonnaise.

Raise heat to broil. Spread garlic mayonnaise on bottom halves of rolls; top with pork. Top remaining halves with vegetables, then cheese. Broil open-faced until cheese is melted and bubbling, about 2 minutes, then sandwich rolls together.