In a medium-sized, heavy saucepan over low fire, melt butter with oil. Saute onions until wilted, then add shrimp.
Stir in flour. Add mushrooms and cook until just wilted, then add crab meat. Season with salt, pepper, and MSG. Pour in cream slowly, stirring constantly to prevent lumping.
Then add sherry in a slow stream, stirring constantly. Adjust seasoning to taste, then remove from fire.
Put 2 heaping tablespoons of the mixture on one side of each eggroll wrapper and roll up.
Arrange crepes on a serving dish. Pour any leftover seafood mixture on top of the crepe, then serve.