Place the raspberries in a bowl and gently mash them with a muddler or fork until they burst and release their juices, creating a bright red, slightly chunky mash.
Use a citrus reamer or juicer to squeeze the lemons, collecting the bright yellow juice in a measuring cup. Strain out any seeds for a smooth lemon juice.
In a saucepan, combine the sugar and 1 cup of water over medium heat. Stir until the sugar dissolves completely, then remove from heat to make a simple syrup. Let it cool slightly.
Pour the cooled syrup into a large pitcher, then add the fresh raspberry mash and lemon juice. Stir well to combine all the flavors.
Pour in the remaining 3 cups of water, adjusting the amount for desired strength. For a fizzy version, add sparkling water just before serving.
If using herbs, gently muddle a few sprigs of mint or basil into the lemonade for an herbal note, or add them as garnish when serving.
Fill glasses with crushed ice, then pour the raspberry lemonade over the ice, allowing it to chill and dilute slightly for a refreshing sip.
Garnish each glass with a sprig of mint or basil if desired, and serve immediately for a cool, tangy, and vibrant drink.
