*I keep my veggie scraps in a ziploc bag in the freezer and just dump these into the slow cooker. Ensure that you have at least a bit of onion in there for flavor and feel free to include the peels. Avoid using any scraps with seeds (i.e. bell peppers) but otherwise any veggie scrap is totally fine. The more greens you include (I love adding kale stalks!) and the longer you cook it for, the darker the stock.