Adding fruit in secondary

I have a belgian dubbel thats been cold conditioning in a secondary for about three weeks now. It's not bad but its not quite what I wanted to be as its lacking the flavors I wanted. I was thinking as an experiment to rack some of the beer off to a smaller 3 gallon carboy and adding in some fruit. I'd only want a very small amount to give a tiny bit of flavor (maybe a pound or so?) I'm not sure what fruit I'd use yet, possibly plums, currants or sour cherries.

I'm not sure how to sanitize the fruit or it is even necessary to do so. Would soaking it in star san work? Or I've also heard some people heating fruit in 160 degree water to sanitize it. If I heated it, should I add enzymes to break down the pectin? Another option is I have a food dehydrator and I was wondering if I dried the fruit myself beforehand if that would effectively eliminate bacteria in the fruit and reduce the risk of contamination. Or maybe I could do all three.

Hard boil a minimal amount of water, toss in your fruit and mash it up, briefly, throw everything in.

Always worked for me,

I did raspberries and used one pint of water per pound of fruit. Boiled up 5 pints of water and added 5 lbs of raspberries. Add all to fermenter.

Would something like this be good to add to a blue moon clone?

As long as your primary is complete, there's no need to sanitize. Wash, freeze, thaw (breaks down the cells), and dump into the secondary.