Method: 

1. Brush both sides of the tuna steak with Canola oil. Season them with salt, pepper and five spice . Place the sesame seeds on a plate and press both sides of tuna steak in sesame seeds to coat.
2. Heat 1 tbsp. of Canola oil over medium-high heat in a large non-stick pan. Add the tuna steak and cook for 1 minute per side without moving them. Let the tuna rest for 5 minutes and slice long clean slices against the grain of the tuna. Set aside. Now cut the cucumber into 1/2 inch cubes and set aside.
3. Mix all the sauce ingredients in a bowl and set it aside. On a large serving plate, place the thinly sliced tuna on it around the plate. Garnish with cut cucumbers and drizzle sauce all over top. Garnish with fried shallots and serve!