Shrimp toast is one of the tastiest bites at the dim sum table. I didn't actually like shrimp toast growing up, but when I finally got around to trying it, I couldn't believe how much flavor was packed into one tiny unassuming square. These are crunchy on the outside, soft in the middle and really dangerous because they are so so addictive.
Put the shrimp and egg white in a food processor and pulse until pasty but still a little chunky. Add the sriracha, salt, sesame oil, black pepper, garlic, scallions and lemongrass and pulse until just combined.
Divide the mixture among the bread slices and spread in an even layer to the edge. At this point, you can freeze the toasts while you heat the oil (although freezing is not totally necessary, it makes for cleaner cuts and easier handling).
Bring 1 1/2 inches of oil to 350 degrees F in a heavy-bottomed pot.
Cut each bread slice into 4 squares and sprinkle with the sesame seeds. Carefully place each piece shrimp-side down into the oil. Fry until golden, 2 to 3 minutes. Remove onto a rack or paper towel. Serve immediately drizzled with sriracha.