Ingredients

• About 1/4 pound ginger, peeled
• 1 cup sugar
• 1 1/2 tablespoons fresh lemon juice
• 1/4 teaspoon active dry yeast
• About 2 quarts water
• a Microplane grater; a funnel; a clean 2-liter plastic bottle with cap

Instructions

1. Grate enough ginger using Microplane to measure 3 1/2 tablespoons, then put in a fine-mesh sieve set over a bowl to collect juice, pressing on solids and then discarding.
2. Place funnel in neck of bottle and pour in 3 tablespoons ginger juice (reserve any remaining for another use). Add sugar, lemon juice, yeast, and a pinch of salt.
3. Fill bottle with water, leaving about 1 1/2 inches of space at top. Remove funnel and screw cap on tightly. Gently shake bottle to dissolve sugar.
4. Let stand at room temperature until plastic feels hard and no longer indents when squeezed, 24 to 36 hours.
5. Chill ginger beer until very cold.