In a saucepan, bring the water and granular monk fruit or allulose sweetener to a boil, stirring continuously until fully dissolved, about 2–3 minutes. Keep the heat at a steady boil with small active bubbles around the edges (visual cue: sweetener crystals disappear).

Add the fresh cranberries, ground cinnamon, and salt, then stir to coat the berries evenly. Let it return to a boil, then watch for berries to begin softening (visual cue: cranberries look glossy and start to split at the seams).

Simmer for 10–12 minutes, stirring occasionally, until the berries burst and the sauce thickens enough to lightly coat a spoon. Visual cue: the mixture looks thicker and turns uniformly red with burst berries visible.

Remove from heat and stir in the orange zest, then taste and add more sweetener if needed for your preference. Visual cue: zest disperses as bright flecks and the sauce looks smooth and glossy.

Cool the sauce to room temperature, then cover and chill before serving. Visual cue: it thickens further and holds shape when spooned, around 2 hours in the refrigerator.