Open Faced Steak Sandwich with herb mayo

Oh Martha how do I love thee! We started making this delicious sandwich last summer and we can't stop. It is the perfect combination of tender beef with just the right amount of herb mayo and peppery, crisp arugula. It is an open faced sandwich but could work as a regular closed sandwich but we personally think that's too much bread and it ruins the flavor of the beef. This is a perfect picnic meal for lunch or dinner. Again we have changed the recipe up slightly from the original version. Here we go:

1 tablespoon of olive oil
1 1/2 pounds tender cut of beef (we usually use a flank steak, but we have used a sirloin steak but there is more fat to trim off)
Coarse salt and freshly ground pepper
4 cloves Roasted garlic (roasting garlic is simple take the cloves and put them in foil and sprinkle them with olive oil, wrap them up in the foil to make a pouch and put into a 400 degree oven for about 15 minutes or until the garlic is soft and spreadable.)
1/2 cup mayonnaise
1 tablespoon of fresh lemon juice
1 tablespoon of chopped fresh flat leaf parsley
1 teaspoon of chopped fresh thyme
1 tablespoon of chopped fresh marjoram
1 baguette or sourdough loaf, sliced into sandwich size pieces
1 cup baby arugula

1. Preheat oven to 425 degrees. Heat oil in a large ovenproof skillet over medium-high heat. Generously season beef with salt and pepper. Add to skillet, and brown on all sides, about 10 minutes total. Transfer skillet to oven.
2. Roast until beef registers 130 for medium-rare, 20-25 minutes. This time depends on how thick your beef is. Take beef out and let stand for 15 minutes. Cut into 1/4 inch thick slices.
3. Meanwhile, mash garlic with fork in a small bowl. Stir in mayonnaise,lemon juice, and herbs. Season with salt and pepper. You can store this in your refrigerator for up to 1 day.
4. Toast your bread. Spread 1 tablespoon of mayo on each bread slice. Top with beef. And just before serving add arugula and season with salt and pepper.