Chop the celery and carrots into 2-inch (5 cm) pieces.
Peel the onions. Chop them in half.
Put all the ingredients directly into the pot. Add water until you just cover the ingredients. We’re using an Instant Pot (also called an Instapot). You can also put it into a giant stock pot.
Set the Instapot to the Soup setting on Low Pressure and Normal. Turn it on and come back once it's done. If you’re using a traditional stock pot, then turn the heat on until the pot boils, then lower the heat until simmer. Allow to cook for at least 3 hours.
When the broth is done, it should be dark brown. Put a strainer over a big bowl. Strain the broth. Discard the ingredients.
Enjoy your beef broth! You can serve it alone with salt and vegetables. Or you can use it in a recipe like Chas’ French Onion Soup.
Notes
You can throw just about any old vegetable in there that’s been hanging around the fridge. But don’t slack off with the stock bones. Get the best you can find!