Put shallots in boiling water and cook for about 2 minutes. Pour onto a sieve, rinse under cold water and drain. Cut off the root with a knife and press the shallot out of its skin.
Peel and finely chop the garlic. Wash the rosemary, dab dry and pluck the needles from the stalk. Bring the stock to the boil. Caramelise sugar in a pan until golden brown and add hot stock and vinegar.
Cook while stirring until the caramel has dissolved. Add shallots, garlic, rosemary, a little salt and pepper and simmer covered for about 5 minutes. Then continue cooking without the lid for about 5 minutes until the caramel stock is thick.
Wash the steaks, dab dry and spread thinly with mustard. Heat oil in a pan and fry the steaks for about 4 minutes, turning them over. Finally, salt the steaks and arrange them on a plate with the caramelized shallots.
Fresh baguette tastes good with it.