In an 8 or 10-quart soup pot, warm the oil over medium-high flame until shimmering—a minute or two. Add chicken; season with a teaspoon of salt, ½ teaspoon pepper, and cayenne, if using. Sauté until pieces are about half-way done, but still somewhat pink at center. Tip in onion, fennel, and celery; season with the herbs (sage, thyme, dill, bay, and parsley) and another ½ teaspoon salt. Reduce heat to medium and cook, stirring regularly, for 10 minutes or until vegetables are nearly tender, adding garlic for last two minutes.