To make the roasted garlic mayonnaise, preheat oven to 400 degrees. Cut 1/4 inch off the top of the bulb of garlic to expose the cloves beneath, but do not peel the garlic, you want to roast it in the skin. Place clove on a piece of aluminum foil, place butter on top, pour lemon juice over the garlic and sprinkle with kosher salt. Bring up all sides of aluminum foil and twist together to close. Cook for 60 minutes or until garlic cloves are soft and golden in color.

Let the garlic cool slightly, about 10 minutes. Squeeze into mayonnaise and stir to combine . Chill until ready to use.

In a frying pan, heat olive oil and butter together. When butter has melted add onions and jalapenos. Cook over medium heat for 20-25 minutes, or until onions and jalapenos are soft and caramelized.

To assemble the sandwich, spread garlic mayonnaise on each half of the bread slices. Layer pork, caramelized jalapenos and onions, cilantro sprigs and romaine lettuce leaves on bottom bread slice and top with the remaining slice. Serve hot.