Pistachio filling in lamb
Gear mentioned in this thread:
I don't understand what you mean by making a small insert. Are you using a cutlet, a chop or a roast or are you going to use a die to pop out a circle replacing it with the mix then sautéing it up? The only kind of filling I can think of is using a wet bread stuffing to bind the pistachio's, that should keep the color you seek, however, if you pan sear it, it might brown it off losing the color effect you seek. More details would help the vision.
Haven't specifically done this, but make a pistachio paste log (small enough to fit your cut in the lamb). Roll it in crushed toasted pistachios. Sprinkle it with a combo of transglutaminase and gelatin. Roll it up in cellophane like a compound butter and let it sit in fridge overnight. Cut to length and insert into lamb.