I went grocery shopping yesterday and bought tons of fresh vegetables, but I still had some random veggies left over from the week before, so I made a vegetable stock with them before they went bad.

1 tablespoon olive oil
1 large onion
2 stalks celery, including some leaves
2 large carrots
1 bell pepper, chopped
1 bunch of asparagus stems
8 cloves garlic, chopped
8 sprigs fresh parsley
6 sprigs fresh thyme
2 bay leaves
1 teaspoon kosher salt
1/2 teaspoon black pepper
2 quarts water

Chop washed vegetables into 1-inch chunks.
Heat olive oil in a large pot. Add all the vegetables and spices. Cook over high heat for 5 to 10 minutes, stirring frequently.
Add water and bring to a boil. Lower heat and simmer, uncovered, for 30 minutes. Strain. Discard vegetables.
Keep refrigerated and use in a week or freeze it for later use.