For a smoother texture, ensure the oats are processed into a very fine powder before adding.
You can substitute fresh vegetables for the frozen mix; just reduce the cooking time slightly since fresh veggies may cook faster or slower depending on the type.
Use sharp cheddar for the best flavor profile. Mild cheddar may result in a less distinct taste.
Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat gently on the stove, adding a splash of milk if the soup has thickened too much.