Mix the basil, thyme and the black pepper together. Season the tuna with the mixture. In a hot saute pan, add the olive oil and sear the tuna until cooked rare or to desired temperature. Remove the tuna. Then add the bok choy with the wasabi, fish stock and the soy sauce to the hot saute. Reduce the stock by a quarter. Remove from heat and ladle the soy wasabi broth into the bowls and place the cooked tuna on the top of top of the bok choy.