If you could only use one lure...

[olslewfoot]

I use flies that I have tied. Usually small (size 10) with a chunk of night crawler. Black seems to be the magic color during the deep dark winter months. a bright orange bead seems to help as the season wears on. Tying my own jigs/lures is incredibly gratifying and humbling at the same time. It stinks when your fishing buddy is catching fish on the new great jig that he just bought at the local sporting goods store, but there is nothing more gratifying than catching fish on a fly that you worked hard on during the "off" season.
I can't believe that nobody has mentioned the super deadly ACME kastmaster. I have caught more trout on that lure than anything I have ever used. It is my secret weapon when my flies are not catching the fish.

[DawntoDusk]

3" to 4" white plastic tube jig. Trout will just devour them, even when the bite is slow

[Wyo-Fisher]

1/8oz jig head with cut'r bug body, tipped w/meal worm

[lefty2053]

Gold Hot green Slender spoon is my go to lure. I found a new Jig I used last time out and caught 5 Trout on my Lip Ripper/Dead Stick. It is a 3" long flat type worm. White with a red jig head. Fish loved it and once they got onto it would quite. I tipped it with a small chunk of worm.

[Jigmup]

Swedish Pimple

x2

[river rat78]

So far I've been doing pretty good with 1/4oz slender spoons no bait. Still too early for me to say since this is the first time I've caught trout threw the ice.

[Trout Sen-Sei]

very small Kastmaster 1/20 oz in gold or shrimpo in small size. Have caught rainbows up to 25inches on them.

[TroutTackler]

Small to medium size all silver Kastmaster with a red hook

[TroutTackler]

or a hand grenade

[Hyland33]

For those of you using Swedish pimples, do you put bait on them too or just use them as is?

[dekatronic]

I'll go old school and go with a Williams Lite bimetal spoon and a #6 or 8 bare hook tipped with worm. 

[fishing207]

Mine would have to be a size 2 Chartreuse colored Swedish Pimple. Caught my first ever Brookie on it so it may have some sentimental value but I always make sure it's with me

[winston6wt]

Hyland33, I've been tipping my pimples with maggots and finding that if the bite is slow it seems to entice a strike. I like chartreuse or silver and chartreuse.

[Sodusitous]

Smallest Pimple gold with cracked ice - Tipped with minnow
head or perch eye -Spikes in a pinch.