Begin by heating olive oil in a large pan over medium heat. Once the oil is hot, add the diced onions and sauté until they turn translucent, which should take around 3-4 minutes.

Add the minced garlic and sliced mushrooms to the pan. Cook for an additional 5 minutes until the mushrooms begin to take on a golden-brown hue.

Add the Arborio rice into the mixture and cook for about 2 minutes, ensuring the rice is thoroughly coated with oil and well-mixed with the other ingredients.

Add the diced tomatoes, excluding the juice, and continue to cook for an additional 2 minutes, stirring occasionally.

Gradually pour in the vegetable stock, one ladle at a time, while stirring continuously. Allow each addition of liquid to be absorbed before adding more. Continue this process until the rice reaches a creamy consistency and is cooked al dente, which should take approximately 20-25 minutes.

Season the risotto with dried oregano, dried basil, salt, and black pepper. Stir thoroughly to evenly distribute the seasonings.

Take the risotto off the heat and let it rest for a minute. Taste and adjust the seasoning as needed.

Serve the Tomato and Mushroom Risotto hot, garnished with fresh basil leaves and a generous sprinkling of grated Parmesan cheese.