To a large pot, add the vegetable scraps, garlic, and salt. If you are adding any optional flavor boosters, add those now, too. Pour water over top until the vegetables are completely submerged and some scraps start to float.
1 gallon freezer bag various frozen vegetables scraps, 3 cloves garlic, 1 teaspoon salt, water, as needed, ½ ounce dried mushrooms, 1 tablespoon whole black peppercorns, 1 vegetable bouillon cube, ¼ teaspoon cayenne pepper or crushed red pepper, 1 tablespoon miso paste