Simple. Roll your chimi ike a large egg roll, tight and sealed with egg wash or sour cream in a pinch. Load them in the bag and put in the sous-vide for a half-hour or so, until reaching an internal temperature of about 140 degrees, then you can flash-fry and JUST KIDDING!!!
It just so happens I spent 3 1/2 years at the best Mexican Restaurant in the country; the country was Bermuda but we were it! The trick with a chimichanga is to get it hot and melted all the way through in the fryer (or the pan on top of the stove at home)without burning the shell. We would put one basket inside of another and listen tor the steam escape in the oil. Roll them nice and tight like an egg roll, no air pockets or leaks, and no more than 2-21/2 inches through the middle. Usually we would roll a nice, big, fat burrito; these are difficult to fry. Actually, one of the best ways if you are not pressed for time i.e. a full dining room dot them with manteca or butter at home and bake at 350 until a nice, even golden brown.
Hax the Cook CLEAVERS RULE!!!