In a large pot or Dutch oven, heat olive oil over medium-low heat, add in the carrots, celery, onions, and potatoes. Sauté until the vegetables have slightly softened, 8 to 10 minutes. Add in the garlic, red chili flakes, nutmeg, and sauté for an additional 2 minutes.
Stir in the vegetable broth, barley, and bay leaf and season with salt and pepper. Simmer covered until the barley is soft, about 30 minutes.
Stir in the kale and simmer for several more minutes until it has wilted and is cooked through, 2 to 3 more minutes. Discard or compost the bay leaf . Taste and add salt and pepper, if needed.