To make the flavoured butter, heat the oil in a small pan, add the shallots and fry gently for 6-8 minutes until golden brown. Leave to cool, then beat into the butter with the peppercorns, mustard and a quarter teaspoon of salt. Scrape out onto a square of parchment paper and roll into a cylinder, twisting the ends to secure. Chill for at least four hours – up to 24 hours is fine.
Trim the rib-eye steaks of any excess fat, then place in a non-metallic dish and add the olive oil, garlic and thyme. Cover with clingfilm and leave in fridge to marinate overnight.
Remove the steaks from the fridge at least half an hour before you wish to cook them, then shake off any excess marinade and season to taste. Grill, barbecue or pan-fry the steaks over a fierce heat for 6-7 minutes for medium rare, or to your liking. Allow to rest for 5 minutes on warmed serving plates.
Remove the flavoured butter from the fridge and remove the paper, then cut into slices. Place butter slices on top of the grilled steaks and add a baked potato and some mixed salad to each plate to serve.