Cut the top sirloin into 1-inch cubes. Coat the sirloin cubes in flour and brown in the oil in a Dutch oven.
Slice the onions thinly. Add the onions to pan and sauté until they are translucent. Add the water, carrots, potatoes, celery, beef bouillon cubes and Worcestershire sauce to the pan.
Reduce the heat to low and cook for 45 to 60 minutes or until tender.
Season the stew to taste with additional salt and pepper. Remove 1 cup of beef broth to a mixing bowl.
Add the sour cream to the removed broth and whisk thoroughly.
Add the broth and sour cream mixture back into pan and stir until incorporated.