Heat 1 to 2 inches of oil in a saucepan or deep fryer over medium-high heat.
Stir tempura mix and water together to make a loose batter.
Cut tough ends from the bottom of the asparagus spears. Dip into the batter, making sure spears are evenly coated.
Carefully add 5 to 6 asparagus spears to the hot oil. Fry until they float to the top, 30 seconds to 1 minute. Drain on paper towels and season with sea salt. Repeat with remaining asparagus.
