Julien moved to the United States "as cook to the celebrated Dubuque, who was a refugee from the French Revolution." Prior to 1793, Julien had served as "steward to the Hon. M. LeTombe, consul of the French Republic." Other friends and associates included Jean Anthelme Brillat-Savarin.
The Restorator opened in July 1793: "a resort where the infirm in health, the convalescent, and those whose attention to studious business occasions a lassitude of nature; can obtain the most suitable nourishment. ... Spirits are not to be used; ... and all gaming is disallowed. ... Excellent wines and cordials, good soups and broths, pastry in all its delicious variety, alamode beef, bacon, poultry, and generally, all other refreshing viands, will be kept in due preparation: and a bill of fare will be kept ... from which each visitor may command whatever may best suit his appetite."
The business first stood on Congress Street "opposite the Quaker's meeting house" in the Financial District, then in 1794 settled on Milk Street (corner of Congress St.) in "the house lately occupied by Mr. Thomas Clements." The building had been erected in 1670-1671 by Henry Bridgham. Julien's was "agreeably situated to receive the fresh air -- which is so necessary for the convalescent and strangers." The establishment was referred to as "Julien's," the "Boston Restorator," "Mr. Julien's French Restorator," "Julien's Restorator," or "The Restorator."
According to food historians Julien's "public eating house ... was famous for his soups and stews, and he was nicknamed the 'Prince of Soups.' He is credited with introducing to America the julienne soup, a composition of vegetables in long, narrow strips. Julien specialized in making turtle soup." Julien's advertisements for the soup emphasized medical justifications: "Turtle soup. Much has been said on its efficacy in purifying the blood by Tissot in his celebrated dissertation on the subject, and by Buffon, the great naturalist, who discovered the beneficial nature of amphibious animals. Those who use this soup must not expect that it be made strong with spice, but from ingredients clear and light." "Many celebrated physicians have recommended it. ... As the first establishment of a restorator in Paris was not for Epicurians -- but for the benefit of those invalids who stood in need of light substance, nourishing and strengthening to their stomacks, it was recommended for the purpose by the Academy in Paris. Citizens of the above description are invited to call and try the virtue of Julien's turtle soup." Julien stressed the healthiness of other items available to his patrons, such as "Naples cordials, syrup of vinegar, syrup of orgeat, and white Bourdeaux wine, all of which are calculated for strengthening and invigorating the system of nature during the heat of summer."
The particulars of Julien's style of business and its inspiration to competitors resonated culturally, for example in a literary spoof in the New England Palladium newspaper, 1801: