I always add a variety of different seasonings/whatever fresh herbs I have on hand. Works well with rosemary, thyme, dill, and chives. I add a pinch of nutmeg every time, I triple the garlic and sauté it with the onion so it actually flavors the soup. I always add at least two diced carrots and celery sticks and usually most other veggies hanging out in my fridge like a seeded jalapeño pepper or diced leeks or mushrooms. Really good base to add whatever you want to, honestly.
