Slice the onions first. Now get the pot really hot and add in the beef. Brown it, then remove it from the pot.
Add in the onions. This part takes awhile and you kinda need to watch it. Cook the onions on a high heat stirring fairly often and scraping the bottom of the pot to prevent too much sticking. Add your herbs and be sure to season with salt and pepper.
After about 20 minutes the onions should be reduced to about ¼ of the original bulk and be nicely browned. Pour in the stock, and return the beef to the pot.
Strain and rinse the beans and add them in. Add about a ¼ cup of vinegar. Taste the broth and adjust seasonings (salt, pepper, vinegar, herbs) as needed. Simmer about 15 minutes.
Pour into oven safe bowls and top with a slice of bread and some cheese and broil to melt and lightly brown the cheese.