Shepherd's Pie

1 small onion, chopped
1 lb ground beef
1/2 tsp salt
1/4 tsp pepper
1 can green beans
1 can (10.5 oz) tomato soup
2 C. mashed potatoes

Heat oven to 350 degrees. Cook onion in oil until transparent. Add meat and cook until brown. Add seasonings, drained beans and soup. Pour into 1.5 quart baking dish. Spoon mashed potatoes over mixture. Bake 30 minutes.