In a medium saucepan, combine the vinegar, 1/2 cup water, chilies, ginger, sugar, and salt. Bring to a boil and simmer until the sugar and salt dissolve, about 2 minutes. Remove from heat. Add the red pepper flakes and let sit for 15 minutes.
Place the zucchini in a large bowl. Pour in the vinegar brine and let sit at room temperature for 1 hour, stirring occasionally. Zucchini pickles can be kept in the refrigerator for 1 week.