Start by cleaning the vegetables, washing them thoroughly. Then peel the potatoes and cut them into fairly large chunks. Move on to the carrots: trim them, peel them, and cut them into similarly sized pieces. Divide the celery into two or more parts, depending on the size. Trim the zucchini and cut them into chunks. Proceed by cutting the tomatoes in half, and finally, peel and cut the onion in half. If the chard leaves are too large, divide them in half.

Place all the cleaned and cut vegetables into the pressure cooker, cover them with two quarts of water, and close the lid. Set the pot on the stove over medium-high heat. When it starts whistling, lower the heat to minimum and continue cooking for 30 minutes. After this time, turn off the heat and open the pot only when you are sure all the steam has been released. If you don’t have a pressure cooker, cook the broth in a regular pot for about an hour, leaving the lid slightly ajar.

Adjust the salt to taste and strain everything through a sieve to collect the vegetables. Your vegetable broth is ready to be used in your recipes.

To avoid wasting the vegetables used for the broth, you can prepare a delicious vegetable puree by blending them with an immersion blender or alternatively with a food mill until you get a smooth and homogeneous cream. Serve the puree drizzled with a little olive oil and accompanied by some croutons.