In a heatproof container, bring 4 cups of filtered water to a rolling boil. Add 1/4 cup of dried butterfly pea flowers, stirring gently. Let steep for about 5 minutes until the water turns a deep cobalt blue.

Carefully strain the butterfly pea flowers from the steeped water using a fine-mesh sieve, ensuring only the blue liquid remains. Transfer to a large pitcher.

Add your desired amount of natural sweetener to the blue lemonade. Stir gently until dissolved, adjusting sweetness as needed.

If desired, fill glasses with ice cubes. Pour the blue lemonade over the ice.

Drizzle or squeeze freshly squeezed lemon juice into each glass and watch the color change to purple.

Garnish each glass with a slice of lemon or a sprig of fresh mint. Serve immediately.