Combine first 7 ingredients; mix well. Chill thoroughly. Trim core end of cabbage to form a flat base. Fold back several outer leaves of cabbage. Cut a crosswise slice from the top, making it wide enough to remove about a fourth of the head; then cut and lift out the inner leaves from the cabbage to form a shell about 1" thick. A grapefruit knife works well to hollow out the cabbage.
Spoon dip into the cavity of cabbage and sprinkle with a little parsley. Depending on the size of the cabbage, you may need to double the dip recipe. Serve with snow peas.
