In a large stockpot over medium heat, add the olive oil and the pancetta. Cook until the pancetta is beginning to crisp. Remove the pancetta and place it on a paper towel-lined plate to drain.
Add the celery, carrot, onion, and leek to the pot. Allow the veggies to cook until they begin to soften. Add the pancetta back into the pot along with the minced garlic and cook.
Add the hand-crushed tomatoes, chicken broth, red pepper flakes, bay leaves, thyme, salt, and pepper to the soup pot. Lower the heat to medium-low and simmer for 10 to 15 minutes.