Preheat oven to 450 degrees F.
Rinse or brush dirt from vegetables but leave skins and peels on unless there are any bad spots. Cut garlic head in half, across the cloves. Cut all other vegetables into large chunks (1 to 2 inches), reserve parsley, peppercorns, bay leaves, parsley and miso.
Place vegetables and garlic on a lined or greased baking tray large enough for the vegetables to be in one layer. You may need 2 trays if you don't have one large enough. Drizzle with olive oil.
Roast for 40 minutes, stirring half way through.
Remove vegetables from oven and place in a pot large enough to hold all ingredients, including water.
Add bay leaves, peppercorns, and parsley.
Mix miso with 1/2 cup hot tap water, stir with a fork to dissolve and remove lumps. Add to pot along with 4 liters of cold water.
Bring to a boil and reduce heat to a gentle simmer. Continue simmering for one hour.
Strain and discard vegetables. Let cool and place in containers.
Vegetable can be kept in the fridge for one week or in the freezer for 6 months. If freezing, make sure to leave space at the top of the container to allow for expansion. Otherwise the lid could pop off.