In a 2 gallon heavy pot melt butter over medium heat and add the onion and shallots. Slowly cook until very dark brown but not burned.
Add a little broth and scrape the pan clean. Simmer until broth is evaporated and onion begins again to stick to the pan and get dark.
Add a little more broth and scrape pan again. Add the potatoes. This little doll worked very hard to cut all the potatoes.
In a separate container, whisk the flour into the remaining beef broth. Pour the beef broth into pot with the onion and potato. Your onions should be very dark colored.
Stir in the seasoning: thyme, dill, celery seed, pepper and zest. Simmer this 15-20 minutes until the mixture thickens and no starchiness is detected when tasted.
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