I agree with John Lawson 100 percent, he makes a good point if you can bother to read through all the wishy-washy double talk!
(Ain't nuthin' wrong with speakin' your mind!)
I'm sure this is what John meant, but in case he didn't make it clear enough, and at the risk of stating the obvious, use the water on parts ONLY, not assembled pieces.
(Strip the slide before you soak it down.)
I've used the boiling water many times myself, and it's great for de-greasing and flushing out the stubborn stuff, but you don't have to go so far as to use actually boiling water.
If you've got a good water heater in your house, (hot enough that you don't want to stick your hand under the hot water) that will do the job just as well, but you have to leave the part under the hot water long enough for the part to reach roughly the same temp as the water.
This does two things.
1. Flushes out all the gunk.
2. Causes the water to evaporate very quickly.
Have Q-tips on hand to reach in and clean all the nooks, crannies, and tunnels, and to re-lube them as well.
As to what sort of lube to use, I'll not get too detailed and just ditto Mr. Lawson. The one thing I do want to add though, is to mention the judicial application of a good gun grease where it's called for.
A tiny dab on the back of the trigger stirrup, and maybe a dab on the (side) bearing surfaces of the hammer.
My general rule of lube, is that if after lubing your pistol, you would not want to wear it tucked in the waistband of your best suit, there's WAY too much oil.
(Kinda the same thing as the white glove test I suppose.)
Remember, best lube is measured in DROP and DAB, anything else is excessive.