Sukiyaki

3 tablespoons cooking oil

1/4 cup sugar

1 

1/2 pounds club steak , trimmed of fat, sliced very thin

10 scallion s including green tops, cut diagonally into 1-inch lengths

3/4 cup canned low-sodium chicken broth or homemade stock

2/3 cup soy sauce

1/3 cup sake or dry white wine

1/2 pound soft tofu , drained and cut into 1/4-inch cubes

1/2 pound napa cabbage , cut into 1-inch pieces

1/4 pound mushroom s, quartered

1/2 pound spinach , large stems removed and leaves washed