Start with a bag of riced cauliflower or make your own. See prep tips, below.
Place onions and celery on a microwave-safe plate. Cook in the microwave for 2-3 minutes, to soften.
Add olive oil to a large, nonstick pan and heat over medium-high heat. Add garlic, softened onions/celery, and sauté for 2 minutes.
Mix in cauliflower rice, sage, salt, and pepper. Cook and stir for about 2 minutes. Stir in chicken broth and continue to cook for 3 minutes. Stir often.
Add mushrooms, sausage pieces, and continue cooking for another 5 minutes. Stir often.
Serve warm or store in the refrigerator for up to 5 days.