Combine the garlic, soy sauce, sugar, sesame oil, and chili oil. Place the green onion into ice-cold water.

Coat the tuna with the vegetable oil and salt both sides liberally. Heat a heavy frying pan over high heat until just smoking. Place the tuna in the pan and sear until a good, brown crust forms. Turn over and brown on the other side. The tuna should remain rare. Remove from the pan.

Strain the soy sauce mixture through a fine sieve, pressing down on the garlic to extract the flavor. Discard the garlic. The soy mixture may be made up to 1 day in advance. Cover and refrigerate.

Drain the green onion and roll in a paper towel to dry. Core the pear and cut into ¼-inch cubes.

Cut each piece of tuna into 12 thin slices. Using 3 slices per plate (or 6 for a main course), arrange in overlapping slices on 8 (or 4) plates. Drizzle with the soy sauce mixture. Place 1 teaspoon (5 mL) of mayonnaise on top of the tuna and top it with a mound of the pear. Drizzle any remaining sauce over the tuna and sprinkle with the sesame seeds, pine nuts and green onion. Serve immediately.