In a medium size bowl toss soba noodles with 2 teaspoons rice wine vinegar and 1 tablespoon sesame oil, set aside.
Wash and rinse then drain the spinach. Heat a saute pan and add spinach. Toss for about one minute, until leaves are just wilted. Season with salt and pepper. Arrange on a plate.
Heat another saute pan. Slice the tuna loin into two triangles. Toss in the marasala tikka, covering all sides with a thin layer. Place both pieces of tuna in the hot pan and sear for no more than 30 seconds on each side (for rare tuna). Remove from the pan.
Slice the tuna into 1/4-inch slices. Top the plated spinach with noodles and arrange the tuna on top