Cover peeled, chopped radishes with water in a medium pot and boil for 10 minutes, until fork tender. Drain and set aside.
Heat oil in a deep skillet over medium-high heat. Saute butternut squash, celery, onion, and minced garlic for about 15 minutes, stirring occasionally.
Add boiled radishes, mushrooms, yellow pepper, herbs, and seasonings. Saute for 6-7 minutes more, stirring occasionally.
Add 1 cup water and continue cooking for about 5 minutes more or until veggies are tender and water is evaporated.