Pack 4 resealable rubber-rimmed jars with the cucumber spears, garlic, and ginger, dividing evenly.
Heat the vinegar, water, sugar, and salt in a saucepan over medium-high heat, stirring until the sugar and salt dissolve, 5 minutes. Stir in the sriracha and sesame oil.
Divide the brine evenly among the packed jars and let cool.
Store in the refrigerator for up to 2 weeks.