Peel the garlic, then use a pestle and mortar to bash it with a good pinch of sea salt until creamy.
Crumble in the chilli, pick in the rosemary leaves and add a good pinch of black pepper. Finely grate in the the orange or lemon zest, then bash it all up into a paste and thin down with a good drizzle of olive oil.
Place the steaks in a bowl or sealable bag, pour in the marinade, massage it in with clean hands and leave to marinate, chilled, for as long as you can, preferably up to 8 hours.
Peel the potatoes, then very finely slice using a julienne cutter. Pat the potatoes with kitchen paper so they’re dry.
When you're ready to cook, heat the oil in a heavy-based saucepan and preheat a griddle over a high heat. Grill the steaks for 2 to 3 minutes on each side, for rare, then leave to rest while you cook the fries.
Very carefully, in batches, deep-fry the potatoes for around 5 minutes, or until golden and cooked. Remove with a slotted spoon, and drain on kitchen paper and sprinkle with sea salt.
Serve the chips and steak with the mustard and cranberry sauce or redcurrant jelly.