Combine the strawberries, rhubarb, and chopped apples in a saucepan, spreading them out evenly.
Add honey or sugar, vanilla extract, lemon juice, and salt to the pan, stirring to coat all the fruit evenly.
Place the saucepan over medium heat and bring the mixture to a gentle simmer, with small bubbles forming around the edges.
Reduce the heat to low and cook, stirring occasionally, until the fruit softens and the mixture begins to thicken, about 15-20 minutes.
Use a wooden spoon to gently mash some of the fruit for a slightly chunkier texture, or leave as is for a smoother sauce.
Taste the sauce and adjust sweetness if needed, then remove from heat and let it cool slightly—the sauce will be vibrant and pulpy.
Transfer the sauce to a serving dish or jar and serve warm or at room temperature as a topping or side.
