As soon as the person falls overboard, regain control of the boat, check they are okay and signal your intention to return. Keep an eye on them at all times. Turn onto a reach, sailed correctly when the boom is held a few inches off the shrouds, and the sail still has some (not full) power.
Leave the jib flapping and prepare to tack, allowing yourself plenty of room to slow the boat as you return. Tack and bear away onto a broad reach or reach.