Rinse the berries: Rinse the 4 cups fresh raspberries gently and pick out any stems, leaves, or squished berries.

Crush the berries: Add the rinsed raspberries to a large pot and mash them with a potato masher or the back of a spoon to break them open and release their juice.

Heat gently: Warm the crushed berries over medium-low heat, stirring occasionally, until softened and juicy. Add 2 tablespoons water, if needed if the pot looks dry.

Strain: Pour the hot berry mash into a fine-mesh strainer, jelly bag, or cheesecloth set over a bowl. Let it drip on its own for the clearest juice, or press gently for more yield (juice will be slightly cloudier).

Sweeten (optional): Taste the strained juice and stir in 2 tablespoons sugar or honey, to taste (optional) if you'd like it less tart.

Chill or freeze: Pour the juice into a jar or pitcher and refrigerate up to a week, or freeze in containers or ice cube trays for up to a year.