Bring a small pot with 3 cups of water to a boil over high heat. Thoroughly rinse produce and pat dry. Cut mushrooms into 1/4" slices. Mince garlic. Peel and mince shallot. Stem and mince thyme. After water reaches a boil, reduce heat to maintain a low simmer. Using simmering water to make risotto helps it cook more efficiently because the liquid and rice will be the same temperature. Continually adding cold liquid to hot rice would slow the cooking process.

Place a medium pan over medium-high heat. Add 2 tsp. olive oil to hot pan. Add mushrooms and sauté, stirring often, until lightly browned, about 4-5 minutes. Add 1/2 cup water and beef base to pan and stir to combine. Cut open packages of osso buco and add meat and all juices in package to pan. Bring to a boil, cover with a lid or foil, and reduce heat to low. Cook for 10 minutes, turn meat, and cook for another 10-15 minutes, or until a minimum internal temperature of 165 degrees is reached.

While the osso buco cooks, you can make relish and risotto. Place a small pan over medium heat. Add 1 tsp. olive oil, half the shallots, and garlic to hot pan. Cook for 1-2 minutes, stirring often. Add diced tomatoes (including any juices) and cook until all liquid has evaporated and a thick relish remains, about 6-8 minutes. Add thyme and season with salt and pepper to taste. Set aside.

Place a medium pan over medium heat. Add 2 tsp. olive oil to hot pan. Add remaining shallots and cook 1 minute. Add arborio rice and toast for 1 minute. Add wine and cook until completely absorbed, about 1-2 minutes. Add 1 cup hot water and a pinch of salt and pepper. Cook, stirring constantly, until water has been absorbed. Continue adding water in 1/2 cup increments, stirring constantly, until consistency is creamy and rice is al dente, about 23-25 minutes. Total water added should be about 2 1/2 cups. Add Parmesan cheese and half the butter. Stir to combine, and season with salt and pepper to taste.

Transfer osso buco to a plate. Turn heat to medium-high and bring liquid in pan to a boil. Reduce by 1/3, about 2 minutes. Swirl butter into sauce. Season to taste with salt and pepper and set aside. Reducing sauces intensifies flavor and thickens consistency. Be sure to taste before you season with salt and pepper.

Add a serving of risotto to a shallow bowl or plate. Place osso buco on top of risotto and pour mushroom sauce over. Finish with a dollop of relish on top. If risotto has stiffened, quickly return to medium-high heat and add another 1/2 cup of warm water to return risotto to creamy consistency.