Bring water to a boil in a large saucepan; add rice and salt. Boil 10 minutes; drain.
Combine next 4 ingredients; stir into rice. Cook over low heat 10 minutes. Remove from heat; add butter and onion juice. Stir in 5 egg yolks and cheese, mixing well. Cook over low heat 3 minutes. Remove from heat; cool. Shape into croquettes.
Combine 2 egg yolks and milk, beating well. Dip croquettes into egg mixture; dredge in cracker crumbs, coating well.
Chill croquettes 1 hour. Fry in 1 inch of hot oil (375°) until golden brown. Drain on paper towels.