Roast Beef With Horseradish Mustard Sauce

1 beef bouillon cube 1 1/2 kg sirloin or 1 1/2 kg rolled rib beef 2 teaspoons plain flour 2 teaspoons mustard powder 1 onion , quartered fresh ground black[...]

2 tablespoons coriander powder 1 tablespoon cracked black pepper 2 teaspoons kosher salt 5 garlic cloves , crushed 3 lbs sirloin tip steaks , trimmed nonstick[...]

4 tablespoons mayonnaise 1 teaspoon honey 1 tablespoon mustard 6 slices bread 3 slices beef 1 handful watercress 1 Mix the mayonnaise, honey and mustard until[...]