Heat 2 tsp. olive oil in a pot and add 1/2 onions and sweat 2-5 minutes.
Add 1/2 green beans and stir to combine 2-3 minutes.
Add remainding onions and green beans and stir to combine.
Add salt and pepper.
Add can of tomato sauce and 1/2 cup water.
Lower heat to medium/medium low and cook 30-45 minutes stirring occasionally.
May add additional water if needed. 1/4 cup at a time.