How to Make It
Place raisins in a medium bowl. Bring vinegar and honey to a simmer in a small saucepan over medium-low, stirring until honey is dissolved. Pour vinegar mixture over raisins and set aside to plump, about 5 minutes.
Slowly whisk in oil, about 2 tablespoons at a time, until smooth. (Or transfer raisin mixture and oil to a jar with a tight-fitting lid and shake to emulsify.) Stir in capers, caper liquid, pepper, salt, and thyme. Serve in a small bowl; spoon over open-faced bagels and lox.