Step 1Heat the oven to 200 degrees. Line a rimmed baking sheet with aluminum foil.
Step 2In a large bowl, mix together the salt and Sriracha until the salt is evenly coated with the sauce.
Step 3Spread the salt out in a very thin, even layer. Place the salt in the oven and toast until the salt is completely dried, 2 to 3 hours. Remove from heat and cool. Pulse the salt in a food processor to break up the large chunks. This makes- about 1 cup Sriracha salt, which will keep up to several weeks, stored in an airtight container in a cool, dry place.
Step 1Fill a large heavy-bottom pot with enough oil to come up the sides by about 3 inches. Heat the oil to 350 degrees.
Step 2Meanwhile, in a large bowl, sift together the flour, ½ cup cornstarch, the baking soda and salt. Whisk in the soda water to form a batter. Thin the batter, if desired with a little more soda water.
Step 3Toss the peppers with the remaining tablespoon cornstarch, dusting off any excess. Dunk the peppers, 1 at a time, into the batter, then place in the fryer.
Step 4Deep fry the peppers, a few at a time, until the batter is puffed and lightly golden, 1 to 2 minutes. Remove and drain. Season the peppers with the Sriracha salt and serve immediately.