At what time is the sun directly south in Strasbourg Alsace?

It depends on the time of year. Because the Earth's orbit is elliptical, local noon varies during the year depending on the Earth's position in its orbit. I used Starry Night software to check this and found that local noon in Strasbourg can be as early as 12:12:13 on November 3 and as late as 12:43:27 on February 11 this year.