Place cucumbers in jar. Bring lemon slices, chile, ginger, vinegar, sugar, salt, sesame seeds, and 2 cups water to a boil in a small saucepan and cook, stirring, until sugar and salt are dissolved, about 1 minute. Let cool. Pour brine over cucumbers in jar; cover and chill. Pickles will taste good after a few hours, but for the best flavor wait at least 24 hours before using.Do ahead: Cucumbers can be pickled 2 months ahead. Keep chilled.