Layer the first 4 ingredients, in order given, in 3 1/2 to 4 quart (3.5 to 4 L) slow cooker.
Heat oil in large frying pan on medium. Add beef. Cook 8 to 10 minutes, stirring occasionally, until browned.
Add ginger and garlic. Hear and stir for about 1 minute until fragrant.
Add water, sherry and brown sugar. Stir. Bring to a boil. Pour over vegetables. DO NOT STIR. Cover. Cook on low for 8 to 9 hours or on high for 4 to 4 1/2 hours.
Stir soy sauce into cornstarch in a small cup until smooth. Add to beef mixture. Stir. Add snow peas. Stir well. Cover. Cook on high for about 10 minutes until snow peas are tender-crisp and sauce is thickened.