Combine the sugar and water in a jar or container and shake vigorously until the sugar completely dissolves. This cold method works perfectly and saves you from heating up the stove for such a small batch. If you prefer the traditional method, heat the water and sugar in a small saucepan over medium heat, stirring until the sugar dissolves, then let it cool completely before using.

Roll the lemons firmly on your countertop with your palm before cutting them in half. This breaks down the internal membranes and helps release significantly more juice from each fruit.

Juice the lemons using your citrus juicer, then strain the juice through a fine mesh strainer to remove seeds and pulp.

Repeat the rolling and juicing process with the limes, using the same technique you used for the lemons. Limes tend to be slightly harder to juice than lemons, so apply a bit more pressure when squeezing.

Strain the lime juice through the fine mesh strainer into the same container as the lemon juice.

Pour the combined citrus juice into a liquid measuring cup to ensure you have about 1.5 cups total. If you're slightly short, juice one more lemon or lime to reach the full amount.

Pour the strained citrus juice into a clean glass bottle or jar with a tight-fitting lid. Add the simple syrup to the citrus juice and close the lid securely.

Shake the bottle vigorously for about 15 seconds to fully combine all the ingredients.

Open the bottle and taste a small spoonful of your sour mix. The flavor should be balanced between sweet and tart. If it's too tart for your preference, add simple syrup one tablespoon at a time until you reach your desired sweetness level. If it's too sweet, add fresh lemon or lime juice in the same incremental way until the balance feels right.

Place the sealed bottle in your refrigerator and let it chill for at least 30 minutes before using. The flavors will also meld and mellow slightly as the mix sits.

Keep your sour mix refrigerated at all times in a sealed container. Label your container with the date you made it so you can track freshness. This mix stays at peak quality for about one week and remains usable for up to two weeks.