Heat oven to
400F (205C). Spread rice on a large shallow baking pan and put in oven.
Heat, stirring once or twice, until rice is dark golden brown, about 5
minutes. Remove from oven. Reduce oven temperature to 350F (175C). Heat
mushrooms, 1/4 cup water and lemon juice to simmering in a small
saucepan. Simmer, uncovered, 3 minutes, shaking the pan often. Drain.
Combine rice, mushrooms, butter, boiling water and onion soup mix in 1
1/2-qt (2-liter) casserole. Stir together with a fork. Cover tightly and
bake 30 minutes. Stir lightly with a fork and continue baking,
uncovered, until liquid is absorbed but rice is still moist, about 15
minutes. Good with broiled meat patties, steak or fish.