Make Lavender Syrup: In a small saucepan, combine 1 cup water and 1 cup sugar. Heat over medium, stirring until sugar dissolves. Add 2 tbsp dried lavender buds, bring to a boil, then simmer for 5 minutes. Remove from heat, steep for 10 minutes, then strain into a jar. Cool completely.
Juice Lemons: Squeeze fresh lemons to yield 1 cup juice. Strain to remove pulp and seeds.
Mix Lemonade Base: In a large pitcher, combine lemon juice, ½ cup lavender syrup, and 2 cups cold water (or sparkling water). Stir well. Adjust sweetness with 1-2 tbsp honey or agave if desired.
Add Alcohol: Pour in 4 oz vodka (or gin) and stir gently. Adjust alcohol to taste.
Serve: Fill glasses with ice, pour lemonade over ice, and top with sparkling water if desired.
Garnish: Add a lemon slice and fresh lavender sprig or a pinch of dried lavender buds to each glass.