Combine the raspberries, water, and honey in a small saucepan and heat gently over low heat, stirring just until the honey dissolves and the berries release their juice without boiling, then remove from heat, add the lemon zest, cover, and let steep for about 10 minutes before straining through a fine-mesh sieve and cooling completely.
Add the lemon pulp and the mashed raspberries to a large pitcher and gently muddle together just until juices are released and a light, textured base forms, keeping everything loose and avoiding a smooth purée.
Add the fresh lemon juice, 120 ml of the cooled honey–raspberry syrup, the pinch of fine sea salt, and the ice-cold water, then stir well and taste, adjusting with more syrup for sweetness, more water if the flavor feels dense, or a small splash of lemon juice only if the berry character begins to overshadow the citrus backbone.
Refrigerate for 1–2 hours until fully cold and integrated.
Fill glasses with ice, pour over the chilled raspberry lemonade, and garnish with lemon slices and fresh raspberries.
