The Ultimate Vegetable Stock | America's Test Kitchen

Ingredients

• 2 medium onions (about 12 ounces), peeled and chopped coarse
• 10 - 12 cloves garlic , from 1 head, each clove peeled and smashed
• 8 large shallots (about 8 ounces), sliced thin
• 1 rib celery , chopped coarse
• Vegetable cooking spray
• 1 small carrot , peeled and chopped coarse
• 4 large leeks , white and light green parts only, cleaned and chopped coarse (about 5 1/2 cups)
• stems fresh parsley leaves (from 1 bunch)
• 2 bay leaves
• 1 1/2 teaspoons table salt
• 1 teaspoon black peppercorns , coarsely cracked
• 1 pound collard greens , washed, dried, and sliced crosswise into 2-inch strips (about 10 cups packed)
• 1 small head cauliflower (about 12 ounces), chopped fine (about 4 cups)
• 8 - 10 sprigs fresh thyme
• 1 stalk lemon grass , trimmed to bottom 6 inches and bruised with back of chef's knife
• 4 medium scallions , white and light green parts, cut into 2-inch lengths
• 2 teaspoons rice vinegar