Preheat oven to 220C. For garlic butter, melt 20gm butter in a saucepan over medium-high heat, add garlic and shallot and stir occasionally until tender and fragrant (2-3 minutes). Remove from heat, stir in mustard and paprika, transfer to a bowl and refrigerate to cool. Beat in remaining butter, season to taste, beat in herbs and set aside.
Heat a char-grill pan over medium-high heat. Brush steaks with a little oil, season to taste and char-grill, turning occasionally, until well-browned (5-6 minutes). Transfer to a baking tray and roast until cooked to your liking (3-4 minutes for medium-rare), then cover with foil and rest for 5-10 minutes. Dollop with garlic butter and serve with French fries and rocket.