Roughly chop the cucumber and add to a large bowl.
Whisk together soy sauce, salt, vinegar, sesame oil, and sugar in a second, smaller bowl until the sugar dissolves. Pour over the cucumber.
Heat oil in a saucepan over medium heat. Add garlic, Sichuan peppercorns and cook for 30 seconds or until fragrant. Cool for a minute.
Sprinkle the crushed red pepper over the cucumber. Pour the garlic oil mixture over the cucumber. Serve cold, and garnish with sesame seeds if desired.
Recipe Note
Note: Chinkiang Vinegar is a type of black rice vinegar originating from the city of Zhenjiang, Jiangsu Province, China. It is made by adding acetic acid and bacteria to glutinous rice. Its distinct flavor cannot be replicated by regular vinegar, but if all you can find is plain (unsweetened) rice vinegar, it's a suitable second choice.