Marinated Flank Steak with Wasabi Mashed Potatoes

2 inches fresh ginger root, peeled and grated

1/4 cup tamari aged soy sauce
2 limes, zested and juiced
3 tablespoons vegetable oil, eyeball it
2 tablespoons grill seasoning (recommended: Montreal Steak Seasoning)
2 pounds flank steak
2 1/2 to 3 pounds Idaho potatoes, 4 large potatoes, peeled and cut into chunks
Salt
1/4 to 1/3 cup cream
2 tablespoons wasabi paste 
4 scallions, root end trimmed
Handful cilantro leaves

Preheat a grill pan or indoor/outdoor grill to high.
Combine ginger, tamari, lime juice, oil and grill seasoning in a large seal able plastic bag. Add meat to marinade and coat evenly. Let stand 10 minutes then grill meat 6 to 7 minutes on each side.
Place potatoes in a pot and cover with water. Bring to a boil, salt the potatoes and cook until tender, 10 to 12 minutes. Drain potatoes and add them back to the hot pot. Smash the potatoes with a masher to desired consistency with the cream and wasabi. Adjust salt, to taste.
While potatoes and meat cook, finely chop the scallions together with cilantro and lime zest.
Let meat rest 5 minutes then thinly slice on an angle against the grain. Serve meat on mash potato mounds with a garnish with a generous sprinkling of the chopped scallion-cilantro-lime zest."