In a small pot add the sugar, soy sauce, Mirin, and brandy. Let the sauce reduce till it coats the back of a spoon. and then add the cream. Set aside.
Heat up a pan on medium high. You may use a griddle pan or BBQ to give the tuna grill marks.
Season the tuna with salt and pepper. Be very generous with the pepper you want to coat it completely. Pressing the cracked pepper into the tuna.
Oil the pan and gently place the tuna in the center. Cook for 20 seconds on each side.
Using a sharp knife, slice the tuna into 1/8" slices.
Spoon a bit of the sauce on top of the tuna, and garnish with fried spaghetti and green onions.
Pour the sauce over the tuna only right before serving, because the alcohol in the sauce can change the color of the fish.You can cook the tuna for a little longer if you find it too raw, but since its sushi-grade there is absolutely no problem.Don't skip the crispy spaghetti, the texture plays a big role in this dish, but you can use anything crispy and fried. For example, fried leeks, parsnip, sweet potato, taro etc..