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.
Method:
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.