In a bowl, combine the soy sauce, water, lime juice, brown sugar, hazelnut oil, sambal oelek and garlic. Reserve ½ cup (125 ml) of the mixture for serving.

On a work surface, cut the tenderloin in half horizontally. Thinly slice both pieces, cutting against the grain of the meat.

In a bowl, combine the beef with the remaining marinade. Cover and refrigerate for 1 hour.

Drain the meat and reserve the marinade.

In a skillet over high heat, quickly brown the beef, a small quantity at a time, in the olive oil. Lightly season with salt and pepper. Transfer to a plate. In the same skillet, bring the reserved marinade to a boil (make sure to boil it thoroughly, since it has been in contact with raw meat). Remove from the heat. Pour onto the cooked meat and combine.

Arrange the lettuce leaves on a large serving platter. Top each leaf with slices of beef and pear, then sprinkle with hazelnuts and green onion. Serve with the reserved sauce and steamed rice, if desired.