Direction

1. Working in 2 batches, place onion, leek, carrots, celery, fennel, garlic, and parsley in the bowl of a food processor and pulse until they form a coarse paste, about 10 pulses. Season each batch with 1 tablespoon of the kosher salt. Transfer paste to a large colander set over a bowl and set aside at least 30 minutes to drain. Press down on mixture to remove as much liquid as possible. Discard liquid.
2. Heat 1/4 cup of the oil in a large, deep skillet over medium-high until oil shimmers. Add vegetable paste and spread evenly over the bottom of the skillet. Cook until paste has browned on bottom; about 3 to 4 minutes. Stir mixture well, then spread out again and cook until browned. Repeat stirring and browning mixture another 2 or 3 times, until mixture is fully cooked, has reduced by half, and has deepened in color.
3. Spread paste mixture to the sides of pan and add remaining tablespoon of oil to the center. Add tomato paste. Cook tomato paste in oil until it softens, then mix into vegetable paste. Cook, stirring frequently, until mixture has reached a brown-maroon color and become a thick paste, about 4 minutes. Remove paste from heat and let cool to room temperature.
4. Portion paste into half-cup portions and freeze until solid. Wrap frozen cubes individually in plastic wrap and store in an airtight container in freezer up to 3 months.
5. To use base to make soup, place a 1/2-cup portion of frozen base in a pot with 1 quart water or stock. Add 2 to 3 cups of beans, pasta, and/or chopped vegetables, additional water or stock up to four cups to cover, and simmer until base melts and ingredients are cooked through, about 20 minutes.