Although much good advice has already been given, there would seem to
be ample room left for confusion. So let me try to suggest a somewhat
more systematic, though not necessarily noncontroversial, process:.

(Step 1 - recovering from a squall-induced broach)
In spite of the best-laid weather awareness and avoidance plans
violent squalls CAN strike out of a blue sky.... During the severe 1997
El Nino, as we were struggling to windward 10-15 NM off the coast of
Maui in very light winds, we were struck repeatedly by strong williwaws
spawned by the huge mountain ranges. With all sails up and no fuel
reserves to fire up the iron genny we were only able to recover from
the resulting broaches by slacking off the sheets, waiting for the
vessel to righten itself and then momentarily running off.

(Step 2 - fully or partially furling the jib)
Afraid to lose in a few minutes what had cost us many hours to gain we
would work feverishly to furl the genoa (after blanketing it with the
furling staysail to reduce friction) and then climb on deck to manually
pull the main down to its third reef points. Even with an experienced
helmsman at the wheel, however, working within the sweep circle of the
boom under these conditions makes one feel like a baseball within range
of Babe Ruth's bat! An uncontrolled gybe is almost certainly going to
become a home run.....

(Step 3 - attempting to "heave to")
Therefore, if at all possible, heaving-to is by far the preferred
solution. Instead of trying to tack through the wind it is often
possible to head up far enough to take the pressure of the headsail
(i.e. staysail or partially furled genoa) and then crank the clew over
to windward far enough to backwind the sail while simultaneously
countering the rudder.

(Step 4 - heading up without going "in irons")
If unable to heave to, IMHO the safest option is to return clew and
rudder to their old position and then to keep turning upwind while
tightening and flattening the partially furled jib (or the staysail)
till your vessel is slowly jogging against wind and waves with the
traveler and boom fully to leeward and the mainsheet just tight enough
to keep the boom from slamming around. Chances are that boom and
mainsail are now pointing far enough into the wind to take most of the
pressure of luff and sail slides while your vessel continues to slowly
sail to windward without the need for starting up the engine. If so,
just go ahead and deep-reef, drop or furl the mainsail.

Have fun!

Henk Meuzelaar
S/V "Rivendel II", Port Vila, Vanuatu