Pour the orange juice into a medium saucepan. Add orange zest, diced red bell pepper, minced serranos, sugar, lemon juice, and salt. Stir to combine.

Heat the mixture over medium, stirring until the sugar dissolves and you hear a gentle simmer.

Bring it to a full boil where bubbles rush across the surface; this activates the pectin.

Once boiling, sprinkle in the powdered fruit pectin and stir continuously for 1–2 minutes to prevent lumps.

Let the mixture boil steadily for about 10 minutes, stirring frequently. Watch for the syrup to thicken and cling with a glossy sheen.

When the jelly coats a spoon and the edges look slightly darker, remove from heat and let cool for a few minutes.

Spoon into sterilized jars, leaving a little headspace, and seal. You'll hear pops as jars cool and seal.

Let jars sit at room temperature until completely cool before chilling.