Sort and wash raspberries. Set aside 3 cups of the firmest whole berries. Keep the remaining 1 cup of softer berries for the syrup.

In a small bowl, whisk together the cold water and cornstarch to create a lump-free slurry. Set aside.

In a saucepan over medium heat, combine the 1 cup of soft raspberries, sugar, lemon juice, and salt. Gently crush the berries to release their juices.

Bring to a gentle boil, then reduce heat and simmer for 5 minutes, stirring frequently until the sugar dissolves.

Stir the cornstarch slurry and pour it into the simmering berry mixture. Cook for 1-2 minutes until the liquid becomes a thick, clear, and glossy syrup.

Remove from heat and stir in the vanilla extract. Let the syrup cool in the pan for 5 minutes.

Add the reserved 3 cups of whole fresh raspberries to the warm syrup. Using a silicone spatula, gently fold until every berry is coated and glistening.

Serve warm over pancakes or ice cream, or chill in the refrigerator to serve cold over yogurt and cheesecakes.