Prepare a boiling water bath and enough jars to hold 6 cups of conserve. Place lids in a small pan of water and bring to a bare simmer.

In a large, wide pot, combine the apple sauce, sugar, vinegar, raisins, horseradish, lemon zest and juice, mustard seeds, salt, and cayenne pepper.

Place over high heat and bring to a boil. Reduce heat and cook, stirring regularly, until the volume has reduced and the conserve doesn't look at all watery. My batch took approximately 45 minutes to cook down.

Taste conserve and add a splash more lemon juice, a pinch more salt, or a bit more cayenne pepper, if you so desire.

Funnel conserve into prepared jars. Wipe rims, apply lids and rings, and process in a boiling water bath canner for 15 minutes.

When time is up, remove jars from canner and place on a folded kitchen towel.