Brown both sides of the round steak. Place in dutch oven or crock pot.

Pour in tomatoes, peas, and onion soup mix.

In the oven, bake at 350 for 3 hours.
In the crock pot, cook on low for 8 hours or on high for 4 hours.

Remove steak from dish. Keep warm.

Using a jar for a shaker, place flour then the water (or milk) — shake until no clumps of flour are visible. Bring tomato/pea mixture to a boil and whisk in flour paste. Cook on low for a few minutes until thick. This creates the gravy for mashed potatoes.