Wash rice; add the water. Cook rice; let stand for 15 minutes. Fry luncheon meat slices to desired brownness. Place cooked rice in a large bowl. Combine the 2/3 cup water, the salt, mirin, and soy sauce. Sprinkle 1/2 of mixture over rice; mix well. Use remaining water mixture for moistening rice, musubi mold, and cutting knife. Fill musubi mold 1/3 full of rice; press rice down with inner section of mold. Spread ume on rice; place two slices of luncheon meat, over ume. Add more rice to fill mold; press down again. Remove mold and wrap a sheet of nori around the musubi. To serve, cut musubi in half. Garnish with furikake and benishoga. Makes 10 Luncheon Meat Musubi.
For hot dog musubi:
Cook 4 jumbo hot dogs in 1/2 cup water. Just before water evaporates, add 1/2 teaspoon sake (Japanese rice wine); continue cooking until sake evaporates. Butterfly hot dogs; cut one into thirds. Place one butterflied hot dog and one piece of cut hot dog over ume* and rice in musubi mold. Follow same procedure in making musubi as above. Makes 6 Hot Dog Musubi.
*If desired, use wasabi (Japanese horseradish) or benishoga (shredded pickled ginger) in place of the ume.
For chicken musubi:
Soak 5 boneless chicken thighs in salted water for at least one hour; drain well. Combine 1 cup flour and 1 teaspoon garlic salt; coat chicken and fry or broil until chicken is done. Slice chicken to fit mold. Place chicken over ume and rice in musubi mold. Follow same procedure in making musubi as above. Makes 4 Chicken Musubi.