Need a quick, easy way to make a good first impression on houseguests with a dazzling appetizer course that can be done ahead of time? Buy about a pound of sashimi-grade ahi (Goleta’s Nikka Fish Market almost always has it), trim to steaks about 3/4 inches thick, douse in a teriyaki-lemongrass-paste-sesame-oil sauce, and then crust the soaked steaks with a mix of black and white sesame seeds. Get a cast iron pan quite hot with a sesame-canola oil mix, sear each piece for only about a minute per side, and rest on a wire rack. Once cool enough, wrap in plastic wrap, put in the fridge to chill, and then make a dipping sauce of teriyaki, sesame oil, fish sauce, wasabi, sriracha, and more lemongrass paste. Before guests arrive, pull from fridge, slice carefully, and organize on a plate. Garnish with pickled fennel and dots of wasabi and lemongrass, and serve with the spicy-sweet dipping sauce.