Start with the relish. Take a large frying pan, peel the onion, chop it into little pieces, and chillies, fry over medium heat for about 5 minutes until it becomes a bit soft. Cut the tomatoes in half, add them to the pan, cook for 5-8 minutes until they collapse. Add the vinegar, cook for another 5 minutes. Remove from heat, add the chopped basil, set aside.
Sauce: combine the mustard and mayo, set it aside.
Heat the frying pan to about 200°C until it’s so hot it almost smokes. Add some oil. Grind salt and pepper to a board and roll the fillet in it. Put the steaks in the oil, flip them after 30 seconds. Add the chopped garlic and butter. Keep flipping them every 60 second until it’s ready, bathe them in the butter, don’t forget to sear the sides.
Remove the steaks from the pan, get rid of the butter and garlic, use the remaining oil/butter to toast the ciabatta slices drizzled with olive oil.
To serve, put some sauce on the bread slices, add some thickly sliced steak, put some relish on it, add some ruccola.
Done. Thanks Gordon.