For the soup, begin by chopping the onion and mincing the garlic.
In a large pot, heat one tablespoon olive oil over medium heat.
Add the onion and cook for 1-2 minutes until beginning to soften.
Add the garlic and cook another minute.
Add the ground beef and use a wooden spoon to break it up into small pieces while it cooks. Season with the taco seasoning.
Once the ground beef is cooked (no longer pink) add the drained can of beans, and the diced tomatoes in their juices. Add the stock as well. Cook for 10 minutes until everything is warmed through.
Stir in the milk. Taste and add salt and pepper as needed.
While the soup cooks, you can make the tortilla strips. Do so by cutting the tortillas into strips (I use a pizza cutter to do this) and pan fry in a little olive oil until crispy.
Serve the soup with the tortilla strips and other taco toppings.