Combine water, salt, sugar, vinegar, and pickling spices in a pot and bring to a boil to create the brine.

Allow the brine to cool to lukewarm.

Marinate the beef roast in the cooled brine for at least 24 hours, keeping it at room temperature or a cool place, but not the refrigerator.

Preheat oven to 325 degrees Fahrenheit (163 degrees Celsius).

Place the marinated beef in a roasting pan.

Add a few slices of onion and whole carrots to the roasting pan.

Pour the brine over the beef and vegetables.

Cover the roasting pan tightly.

Roast the beef in the oven for approximately 3 hours, or until the beef is very tender.

Remove the beef from the roasting pan and set aside to rest.

Strain the cooking liquid from the roasting pan into a separate pot.

Bring the strained liquid to a boil.

In a separate bowl, create a flour paste by mixing water, lowfat sour cream, and flour until smooth.

Slowly pour the flour paste into the boiling liquid, stirring constantly to prevent lumps.

Continue stirring until the gravy thickens to your desired consistency.

Slice the beef roast into serving portions.

Serve the sliced beef with Czech dumplings and the prepared lowfat sour cream gravy.