This simple lentil soup is bursting with colors and flavors and is easy to prepare in one pot. Red lentils are a small, orange colored legume that are high in fiber and protein. The celery, carrots, and zucchini also provide an abundance of fiber and nutrients which are helpful for a head and neck cancer patient to keep the immune system strong and promote regular bowel movements. If your mouth is sore or irritated, you can omit the lime juice and reduce or omit the tomatoes.