In a large pot (I use a 3½-quart enameled cast iron Dutch oven), heat the olive oil over medium-low heat. Add the onions and celery and sauté, stirring occasionally, until the onions start to soften and become translucent.
Add the garlic and continue to sauté, stirring constantly, for another minute.
Combine the water and roasted chicken base and add it to the pot along with the carrots, cabbage, and diced tomatoes.
Bring to a boil; reduce the heat and simmer, uncovered, for 20 to 30 minutes or until the vegetables reach your desired level of doneness (I recommend keeping them crisp-tender rather than overcooking them).
Stir in the dried parsley.
Taste and add salt and pepper, if needed.