Preheat the oven to 350 degrees.
Heat up the butter and oil in a large skillet. Put the baby onions and saute for about 5 minutes. Remove with a holed spoon and set it aside while keeping warm.
Add the stewed beef to the pan and cook while stirring for about 5 minutes.
Put the onions back into the pan and add in the rest of the ingredients. Mix well. Pour the whole mix into a casserole dish for the oven.
Put the mix into the oven for 75 minutes.
Skin and halve the tomatoes and add to the dish. Cook for another 20 minutes.