Bring a large saucepan of salted water to a boil. Add the broccoli rabe and cook until tender, about 3 minutes. Drain, squeezing to remove any excess water, and transfer to a serving bowl.
Heat the jelly in a small saucepan over low heat for 2 to 3 minutes. Remove from heat and whisk in the oil, mustard, red pepper, ½ teaspoon salt, and ⅛ teaspoon black pepper.
Drizzle the broccoli rabe with the sauce. Serve warm or at room temperature.