For the Steak:
Combine all the ingredients in a medium baking dish and add the steak.
Toss to coat, cover, and marinate in the refrigerator for at least 24 hours, preferably 2 days.
Bring the steak to room temperature before grilling.
Bring the grill up to heat. Remove the steak from the marinade and wipe off any excess liquid.
Season with salt to taste. Sear the steak for 3 to 4 minutes per side.
Close the grill and continue cooking for 10 to 15 minutes for medium rare.
Remove the steak from the heat and allow it to rest for about 10 minutes.
Cut into ½ inch thick slices
For the White Bean and Shiitake Mushroom Salad :
Preheat the grill and brush the mushrooms with some of the oil. Season with salt and pepper to taste.
Grill for about 3 to 4 minutes per side. Remove and slice the mushroom caps into ¼ inch slices.
Place the warm beans in a large bowl, add the grilled mushrooms, herbs, and tomatoes.
Whisk together the lemon, olive oil, and minced garlic.
Pour over the top of the beans, add the cheese, and season with salt and pepper to taste.
Serve with the sliced Tuscan porterhouse steak. Pass a baguette of fresh Italian bread.