Heat 2 TBSP olive oil to medium heat in large sautee pan or cast iron skillet.
Add 1/2 sliced mushrooms and cook for ~3 minutes without stirring until mushrooms are browned on one side.
Turn mushrrooms and cook for another 3 minutes until browned.
Removed cooked mushrooms from pan. Add another 2 TBSP oil and remaining mushroom and cook for three minutes or until browned on both sides as described above.
Remove mushrooms from pan, season with salt and pepper, and wipe out pan with paper towel.
Return pan to heat and add remaining 1 TBSP of oil to pan.
Add onion, pepper and garlic to pan and sautee until softened, about 4 minutes.
Remove onion, pepper and garlic, place in a small bowl and set aside.
Add zuchinni to pan and sautee for ~3 minutes until softened.
Remove zuchinni from pan, add to pepper and onions and season mixture with oregano, marjoram, crushed red pepper, half of torn basil leaves, salt and pepper.