Step 1

Rinse all the vegetables to remove any dirt or sand. Chop the carrots, celery, onion and leek into 1-inch pieces. To do this more quickly, cut the vegetables into large chunks and add to a food processor along with unchopped parsley. Pulse 5-8 times to chop them coarsely (try not to puree them).

Step 2

Put the chopped vegetables in a large (4-quart) pot. Add the garlic cloves, salt, water and thyme (if using). Bring to a simmer over medium-high heat.

Step 3

Lower the heat to maintain a gentle bubble. Cook 15-20 minutes, uncovered, until the vegetables are soft, but not mushy.

Step 4

Set a mesh strainer over a large heatproof bowl. Immediately pour the broth through the strainer. Cool to room temperature. The solids can be used for soup if they're not too mushy, otherwise discard them into your compost.

Step 5

Transfer cooled broth to glass jars or other sturdy lidded storage container. Store refrigerated up to 1 week, or freeze up to 3 months.