I cook this all the time in summer and even took it along for Christmas day with the Gordons.
On that occasion I served it with a salsa verde which packed a fair punch but we washed it down with some Orange area wines which definitely took the edge off. By the way, yes, sorry you do need the anchovies.
Rub the beef with the cloves of garlic, then rub all over with the flour. Using your hands, massage the seedy mustard into the beef. Roast with a teaspoon of oil in the pan at 200 C until the meat thermometer reads medium.
Let it rest for an hour (please don’t skip this bit!)
Wrap in foil and refrigerate until needed.
Salsa Verde
Soak bread in ½ the oil for 30 minutes, place in a blender with the rest of the ingredients. Blend until a smooth paste forms.