Mustard-Seed-Crusted Prime Rib Roast with Roasted Balsamic Onions
Peer reviewed by UK recipe editorsAuthored by UK recipe editorsOriginally published 16 Jan 2026
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This impressive mustard-crusted prime rib roast is the ultimate centerpiece for a celebratory Sunday lunch or festive gathering. The beef is coated in a pungent garlic and Dijon mustard glaze before being finished with a crunchy mustard seed crust, providing a sophisticated sharp contrast to the rich, succulent meat. Slow-roasted alongside sweet balsamic onions and shallots, the dish develops a deep, savoury intensity that is perfectly balanced by a luxurious homemade horseradish crème fraîche.
As a diabetes-friendly option, this recipe focuses on high-quality protein and heart-healthy aromatics like garlic and onions, replacing heavy flour-based gravies with a light, brandy-infused jus. The inclusion of tangy vinegar and mustard helps to brighten the flavours without the need for added sugar. Serve this elegant roast with a side of steamed seasonal greens for a wholesome and satisfying meal that will delight your dinner guests.
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Ingredients for Mustard-Seed-Crusted Prime Rib Roast with Roasted Balsamic Onions
120ml crème fraîche
120ml double cream
60ml prepared white horseradish
240ml plus 1 teaspoon dijon mustard, divided
4 medium onions, cut into 3/4-inch wedges with some core attached
5 very large shallots (about 450g ), quartered through root end
45ml balsamic vinegar
2 tablespoons olive oil
1 1/2 teaspoons coarse kosher salt plus additional (for sprinkling)
4 garlic cloves, minced
1 4.3kg bone-in standing prime rib roast, trimmed
2 tablespoons yellow mustard seeds
60ml brandy
2 cups low-salt beef broth
Chopped fresh italian parsley
How to make Mustard-Seed-Crusted Prime Rib Roast with Roasted Balsamic Onions
Using electric mixer, beat crème fraîche and cream in medium bowl to firm peaks. Fold in horseradish and 50g mustard. Season to taste with salt and pepper. Cover and chill. DO AHEAD: Can be made 8 hours ahead. Keep chilled. Rewhisk before serving.
Preheat oven to 232°C. Toss onions, shallots, vinegar, oil, and 1 1/2 teaspoons coarse salt in large bowl. Sprinkle roast lightly with coarse salt and generously with pepper. Stir 100g mustard and garlic in small bowl; rub over roast. Place roast, bone side down, in roasting pan. Sprinkle mustard seeds over, pressing to adhere. Roast 20 minutes. Reduce oven temperature to 177°C.
Arrange onion mixture around roast. Return to oven; roast until instant-read thermometer inserted into centre registers 49°C, stirring onion mixture occasionally, about 2 1/4 hours for medium-rare.
Transfer roast to work surface. Tent with foil; let rest 30 minutes. If necessary, increase oven temperature to 232°C and return onion mixture to roasting pan and roast until deep brown and very tender, about 10 minutes. Using slotted spoon, transfer onion mixture to medium bowl.
Place roasting pan over 2 burners on medium-high heat. Add brandy; stir 30 seconds. Whisk in broth and remaining 1 teaspoon mustard; boil until reduced to 300ml jus, stirring occasionally, about 10 minutes. Season jus with salt and pepper.
Slice roast; arrange on platter. Spoon onions around roast. Sprinkle parsley over. Pass dijon crème fraîche and jus alongside.
The king of roasts meets its match in the king of wines. Dijon mustard's pleasant sharpness softens Cabernet's big tannins. With the roast, try the ROBERT MONDAVI 2006 CABERNET SAUVIGNON OAKVILLE (California, $45). The wine's spice and blackberry flavours are perfect with the beef.
Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.
Article history
The information on this page is peer reviewed by qualified clinicians.
16 Jan 2026 | Originally published
Authored by:
UK recipe editors
Peer reviewed by
UK recipe editors

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