Combine white wine, brown sugar, lemon peel, star anise, cinnamon sticks, and vanilla bean in a 5- to 6-quart pan over medium heat and bring to a simmer to create the poaching liquid.

Peel pears, cut in half lengthwise, and core.

Place pears in wine mixture, cover, and simmer, turning occasionally, until pears are barely tender when pierced, about 15 minutes.

Remove from heat and let pears cool in liquid, turning occasionally, for at least 30 minutes, or chill covered for up to 3 days.

Zest, peel, and segment the orange, collecting the juice in a small bowl.

Lift pears from poaching liquid with a slotted spoon and transfer to a large colander to drain, reserving the poaching liquid.

Slice 2 of the pears into about 1/4-inch slices.

To make the dressing, puree the remaining 2 pears and Gorgonzola in a food processor and transfer to a mixing bowl.

Whisk in olive oil, orange zest, salt, pepper, 2 tablespoons of the reserved poaching liquid, and the brandy.

Toss arugula and fennel with some of the dressing.

Arrange orange segments, pears, and walnuts over the dressed greens.

Add a generous grind of pepper and serve with additional dressing on the side.