Peel and chop the onion. Wash, clean and dice the tomatoes. Heat 2 tablespoons of oil, sauté onion, add tomatoes and mustard seed. Season with salt, pepper and sugar.
Boil down for 2 minutes at high heat. Wash the basil, shake dry, pluck leaves from the stems and chop, except for a little to garnish. Stir the basil into the chutney. Wash the meat, dab dry.
Heat 2 tablespoons of oil in a large frying pan. Fry the steaks vigorously for 3-4 minutes on each side. Remove the meat, season with salt and pepper and cover each with a slice of cheese. Arrange with chutney on plates and garnish with basil.
Ciabatta bread tastes good with it.