Preheat oven to 425 degrees F (220 degrees C).
In a large bowl combine Lean Ground Beef (2 pound), Panko Breadcrumbs (1/2 cup), Egg (1), Dried Oregano (2 teaspoon), Worcestershire Sauce (2 teaspoon), Onion Powder (1 teaspoon), Ground Black Pepper (1 teaspoon), Salt (1 teaspoon), and Garlic Powder (1/2 teaspoon) and mix until incorporated.
Roll into 1-ounce meatballs (about 2 tbsp each) and arrange on a large baking tray lined with parchment. Will yield about 38 meatballs. Bake for 15 minutes and remove from oven.
Reduce heat to 350 degrees F (175 degrees C).
While meatballs are cooking, heat Oil (1 tablespoon) in a large dutch oven. Add Mushroom (14 ounce) and sauté until most of the liquid has evaporated and starting to brown.
Add Water (2 cup) and Knorr OXO Beef in a Mug Soup Base (1/4 cup) and heat to a simmer, stirring to dissolve.
Whisk together the Corn Starch (1/4 cup) and Cold Water (1/4 cup). Add to pot, whisking constantly until mixture comes to a boil.
Reduce heat and whisk in Cream of Mushroom Soup (1 can) until smoothed out. Stir in Sour Cream (2 cup), Worcestershire Sauce (2 teaspoon), Dried Parsley (1 teaspoon), Paprika (1/2 teaspoon), and Ground Black Pepper (1/2 teaspoon).
Add meatballs to the sauce and stir gently to coat with sauce. Cover and bake for 30-35 minutes. Remove from oven and serve immediately over noodles, rice or potatoes.