Cook the rice according to the package instructions.
While the rice cooks, dissolve the tablespoon of salt in the 3 cups of water in a bowl large enough to hold the chicken.
Wash the chicken breasts, fillet them in half to make them thinner and soak them in the bowl of salt water for about 15 minutes. After soaking, pat them dry with a paper towel.
In a large skillet, melt the butter over medium-high heat and cook the chicken turning once until both sides appear to be cooked, about 5 minutes each side. When done, remove from pan and set aside.
Preheat oven to 350 now.
Stir in flour and sour cream, whisking to remove any lumps. Stir in the 3/4 cup water and bouillon cube, mixing well to combine (I usually dissolve the cube in the water before I add these). Add the mushrooms and cook, stirring until sauce thickens, about 8 minutes.
Spread the cooked rice in the bottom of a 13x9 baking dish, lay the chicken on top, pour the mushroom sauce over the top and sprinkle the mozzarella cheese evenly over top. Sprinkle lightly with paprika.