I just had to translate "our staff are handpicked" and the expression triés sur le volet (literally, "sorted on the shutter") immediately came to mind. Where does it come from? Expressio tells us that

In the Middle Ages, a "volet" was a piece of material so fine that it "voletait" (fluttered) in the wind. It was used, among other things, to make sieves used to sort seeds; by extension, these sieves were called "volets".
This word survived and in the 15th century, a "volet" was the wooden plate used by women to sort peas and beans.