Dear Professor Fleurant:
Bouillir (to boil), agreed. The word, "booyah," however, comes from the word, bouillon (broth), which the uneducated Belgian could not spell, thus writing down the word he heard. This theory is promoted by Dr. Lester Rentmeester and attributed to his father, Andrew Rentmeester, a Flemish descendant who lived in the township of Preble, Brown County. See article from The Flemish in Wisconsin. It's difficult to believe a school teacher couldn't spell the word bouillon, but that is their story.
From the Walloon point of view, the original "Booyah" was bouillon-- a broth made from boiling a chicken with onion and celery, salt and pepper. The chicken was taken from the pot when sufficiently cooked and used as the main course of the meal, and the broth served in individual bowls. An additional bowl of rice was put on the table with each person adding what he wanted, if any, to the broth. This was related to me by a woman of Belgian descent, born in Kewaunee County in 1895, who lived to be 95 years old. As a young person, she had never seen the style of "booyah" as we know it today. With the Belgians' penchant for frugalness, nothing was wasted. Bits of leftover vegetables gradually were added to the chicken broth-- and later, the chicken, too-- to make a more flavorful soup, almost a one-dish meal.
Yes, there are as many booyah recipes as there are cooks. Some even add caned pork and beans, canned tomatoes, and canned tomato juice, in the hopes of improving the flavor. Those things certainly wouldn't have been available to the "old" Belgian settlers.
And so the Booyah Brouhaha goes on. For years people have been trying to figure out how the concoction originated and what makes it so special. We don't really need a scientific answer. We just eat and enjoy!
Sincerely, Mary Ann Defnet
Letter reprinted with Mrs. Defnet's permission
30 december 1997