Cook country sausage according to package directions in a skillet under done and crumbly.
Transfer sausage to a paper towel lined plate to drain any grease. You may want to use another paper towel on top of the sausage to rid it of any more grease.
Transfer dry sausage to a medium sized bowl.
Add tomatoes, half of the mozzarella, parmesan, Italian seasoning, basil, green onion and stir until well mixed.
Clean portobellos with a dry paper towel. Remove the stems and hollow out the center fibers using a spoon. Place mushrooms top-side down in an 8"x8" glass baking dish.
Stuff sausage mixture into each portobello firmly. Top with black pepper.
Add remaining mozzarella on top of mushrooms before baking.
Bake 10-12 minutes until mushrooms are tender.
Serve hot.
Notes
The parmesan and sausage already give a salty flavor, which is why a pinch of salt is not included in this recipe.