Pour the oil in a large saucepan or wok to about 2 inches deep and heat to 360°F.
In a large bowl, beat together water and egg yolk until frothy. Whisk in flour and corn starch until combined, but not completely smooth.
Dip each pepper into the batter to coat completely, then place in the heated oil. Repeat. Do not crowd the pan.
Fry until golden on all sides, 3-5 minutes. Transfer to a rack or towel-lined plate.
Serve immediately with your favorite dipping sauce.