Preheat oven to 450 degrees F (230 degrees C).

Cut all fat off the lamb.

Mix salt and dry mustard together.

Rub the salt and mustard mixture into the lamb.

Cut slivers of garlic.

Insert the garlic slivers into the meat near the bone.

Place the lamb in a heavy baking dish.

Roast at 450 degrees F (230 degrees C) for 15 minutes.

Reduce oven temperature to 350 F (175 degrees C).

Roast for another 15 minutes.

Mix coffee, cream, and chicken stock together.

Remove the lamb from the oven.

Pour the coffee, cream, and stock mixture over the lamb.

Return the lamb to the oven.

Continue cooking until done, about 25 minutes per pound to reach medium-rare.

Use a meat thermometer to determine doneness: 110 degrees F (42 degrees C) is rare, 120 degrees F (58 degrees C) is medium-rare, and 145 degrees F (68 degrees C) is medium-well done.

Do not exceed 145 degrees F or the lamb will become dry.

For a more succulent roast, remove it from the oven when it's 10 degrees F (5 degrees C) from its ideal doneness.

Allow the lamb to rest for 15-20 minutes under a loose foil tent.

Spoon surplus fat off pan juices for the sauce.

Place the pan over medium heat.

Stir in flour and cook for 2 minutes or until it colors slightly.

Add cream, red currant jelly, and seasonings.

Simmer the sauce for a few minutes.

Carve the rested lamb and serve the sauce separately.