Whether you're serving them to company or family, these crisp, light tempura bites will disappear in a flash! The tender broccolette florets tend to burn quickly, so for best results, cook them in small batches and use a thermometer to monitor the temperature of the oil.
Combine the cornstarch, flour, baking powder, and salt in a bowl and whisk to blend. Add one cup of the ice water and mix with a fork until just combined; add more water if the batter is very thick. It should be about the consistency of heavy cream.
Heat 1-1/2 inches of oil in a deep saucepan over medium heat until hot, 325-335 degrees F on deep-fry thermometer.
Dip the broccolette pieces into the batter. Deep fry the broccolette in small batches until golden, about 2 minutes. Transfer the tempura broccolette to several layers of paper towels to drain and sprinkle with sea salt. Serve hot.