Divide the jalapeños into 2 (16-ounce) lidded jars and place a garlic clove in each jar.
In a small saucepan over low heat, simmer the vinegar, water, sugar, and salt, stirring occasionally, until the sugar is dissolved, about 5 minutes.
Pour the brine over the jalapeños.
Let cool to room temp, then cover and chill for at least 30 minutes.
Store in the fridge for up to 2 weeks.
