Cheese-Quesadillas

In a small pot, mix water with mustard seeds, vinegar, sugar, and salt. Boil for about 2 minutes, then remove from heat. Peel and dice the onion, cucumber, and mango. Halve the chili pepper, remove the seeds, and slice it into strips. Add these ingredients to the vinegar mixture and set aside.
Heat some oil in a grill pan. Grill the steak for 3-4 minutes on each side until cooked to your liking. Season with salt and pepper. Remove the steak from the pan, wrap it in aluminum foil, and let it rest for about 5 minutes.
Cut the baguette rolls in half lengthwise and brush them with the remaining oil. Briefly toast them in the hot grill pan. Halve the garlic and rub the bread halves with it.
Slice the steak thinly. Spread mayonnaise, steak, lettuce, and relish on the bread. Then place the cheese slices on the sandwich and pour the cheese sauce over it. Serve and enjoy!