Roughly chop all of the vegetables into 2-inch pieces; precision is not important.

Fill a large stockpot with the water, add the vegetables, and place over high heat.

When the water comes to a boil, lower the heat to a simmer and add the peppercorns and bay leaf.

Let simmer, uncovered, for 2 hours.

Squeeze the orange into the stock, then add the two halves, skin and all.

Turn the heat off and allow to steep for 15 minutes.

Strain and chill.