1. Heat a large pot over medium heat. Once hot, add oil, onion, garlic, carrots, and celery. Add 1/2 tsp each sea salt and black pepper and stir to coat. Sauté for about 5 minutes or until softened and slightly browned, stirring frequently.
2. Add water, greens, parsley, thyme, rosemary, bay leaves, and another 1/2 tsp sea salt and black pepper and increase heat to medium high until the mixture comes to a boil. Once boiling, reduce heat to a simmer and add tomato paste. Stir to combine and loosely cover (with the lid cracked).
3. Continue cooking for at least 30 minutes, preferably 45 minutes to 1 hour. The flavor will deepen the longer it cooks.
4. Near the end of cooking, taste and adjust flavor as needed, adding more herbs for herby/earthy flavor, salt for saltiness, pepper for a little spice, or tomato paste for “umami” and depth of flavor.
5. Let cool slightly before pouring over a strainer into another pot. Then divide between storage vessels. Let cool completely before sealing. Store in the refrigerator up to 5 days or in the freezer up to 1 month (sometimes longer).

Adapted from Minimalist Baker.