Soak porcini mushrooms in boiling-hot water for 20-30 minutes.

Strain soaking liquid through a fine sieve lined with a coffee filter into a small saucepan, avoiding the sediment.

Boil the strained liquid until reduced to about 1/3 cup.

Wash porcini mushrooms under cold water to remove grit and pat dry.

Chop the porcini mushrooms coarsely.

Bring the reduced porcini liquid to a boil with cold water, salt, and wild rice.

Simmer covered for 45-50 minutes or until rice is tender and liquid is absorbed. Drain if necessary.

Transfer rice to a serving bowl and keep warm.

In a heavy skillet, cook fennel, red onion, and mushrooms in butter over moderate heat until fennel is tender, about 10 minutes.

Add the fennel mixture to the rice and toss to combine.

The rice can be made ahead of time and reheated in a skillet, adding water to prevent sticking.