Trim any surplus fat from steaks. Heat butter in pan, add steaks, sprinkle with salt and pepper; cook until brown on both sides. Remove from pan.
Add finely chopped onion, cook until transparent. Stir in flour, cook 1 minute. Remove from heat, gradually add water, blend well.
Add chicken stock cube. Return to heat, cook, stirring, until thickened. Add tomato sauce, worcestershire sauce and sherry. Season to taste with salt and pepper.
Return steaks to pan, cook gently 5 minutes. Sprinkle with chopped parsley.
Recipe by Country Recipe Book at https://countryrecipebook.com/sherry-sauce-with-steak/