In a 10- to 12-inch frying pan over high heat, combine 1 1/3 cups grain mix (see notes above) and 2 cups fat-skimmed chicken broth. Bring to a boil. Cover, reduce heat, and simmer until grains are tender to bite, about 12 minutes, stirring occasionally. Meanwhile, rinse and finely chop 1/2 pound shelled cooked tiny shrimp. Stir shrimp, 1/2 cup minced green onions, 2 tablespoons oyster sauce, and 1 tablespoon minced fresh ginger into grains. Spoon into 8 rinsed and crisped large iceberg lettuce leaves (about 1/2 lb. total). Roll to eat.