Start by bringing some olive oil in a large soup pot to medium-low heat. Once oil is hot, add in sliced onions. Cook, covered, for 30 minutes, stirring every 5-10 minutes or so. We want the onions to be steamed and slightly browned, not burnt. If you burn your onions it will make the soup taste bitter.
Once onions are soft, add in the minced garlic and stir well, sauteing for about a minute or so.
Then, add in the broth, thyme, and black pepper. Stir, and let simmer for 30 minutes, covered.
After 30 minutes, taste broth and gauge the salt level. It all depends on what type of broth you used. Add salt to taste, and any more black pepper / thyme if you'd like to.
When done, ladle into bowls and serve. It tastes delicious with crusty bread to scoop up the onions!
Enjoy!