In a medium saucepan, add the raspberries, sugar, water, lemon juice, and salt.
Stir gently to combine, then bring the mixture to a boil over high heat.
Once boiling, reduce the heat to medium-low, and let the syrup simmer for 10 minutes. The raspberries will begin to break down, and the syrup will turn a deep ruby red color.
Remove the saucepan from the heat and carefully strain the syrup into a clean bowl or jar using a fine mesh strainer. Use a spoon or spatula to press out all the liquid from the mashed berries.
Let the syrup cool at room temperature for at least 1 hour. Pour into a syrup bottle or mason jar, seal with a lid, and store in the fridge for up to 3 weeks.
Don’t toss the leftover fruit! The strained raspberries make a fantastic topping for yogurt, oatmeal, pancakes, waffles, French toast, ice cream, or even stirred into a mocktail for added texture and flavor.