Step-by-Step Instructions. This is a one-pot, minimal-mess situation that comes together faster than you think.

Cook the rhubarb syrup. Combine 1 cup chopped rhubarb, 1 cup granulated sugar, and 1 cup water in a medium saucepan. Set it over medium-high heat and bring it to a boil. Once it is bubbling, reduce the heat to medium and let it simmer for 7 to 10 minutes. You will know it is ready when the rhubarb pieces have completely fallen apart and the liquid looks thick and pink. Stir occasionally to keep the sugar from sticking to the bottom.

Strain out the solids. Place a fine mesh strainer over a heatproof bowl or large measuring cup. Pour the rhubarb mixture through the strainer, letting the syrup drip into the bowl below. Use the back of a wooden spoon to gently press on the cooked rhubarb and release any trapped liquid. If you want a crystal-clear syrup, avoid pressing too hard. If you do not mind a slightly cloudy finish with more body, press away.

Let the syrup cool completely. This step matters more than you think. If you add hot syrup to lemon juice, it will cook the lemon flavor and make everything taste flat. Set the bowl aside on the counter or stick it in the fridge if you are in a hurry. It should take about 30 minutes at room temperature to cool down to where you can comfortably touch the bowl without burning your hand.

Mix the lemonade. In a large pitcher, combine the cooled rhubarb syrup, three-quarters cup fresh lemon juice, and 2 cups cold water. Stir everything together until it is fully blended. Taste it. If it is too tart, add a splash more water or a tablespoon of sugar. If it is too sweet, squeeze in another half lemon. This is your lemonade, so tweak it until it tastes right to you.

Serve over ice. Fill glasses with ice cubes and pour the lemonade over the top. Garnish with lemon slices, a sprig of fresh mint, or even a thin slice of rhubarb stalk if you are feeling extra. Drink it immediately while it is ice-cold and the flavors are bright.