Arugula In StewSometimes you just have to attempt to minimize your losses. Last year I catered a dinner for 300 assisted by a young chef who came with the highest credentials and education. The meat entree requested was sweet and sour braised brisket of beef. The briskets averaged 17 lbs. untrimmed and had to be fabricated before cooking. It was very time consuming and my young colleague was quite slow, though eager to learn. She insisted that we prepare at least half the briskets using a recipe she'd used many times previously, using carmelized onions and sun dried tomatoes. It sounded interesting, but I was uncertain about using a recipe that I hadn't used previously with success. Long and short: Her sauce was inedible; extremely acidic. The meat, however, was tender and with the sweet and sour sauce I'd used on the other briskets was easily corrected. I dumped her sauce and washed her cooked briskets. Losses were minimized. Sometimes, that's the best you can do.
If the meat in your stew hasn't been embittered by the arugula, wash it and set it aside. Cook some vegetables separately in bullion; thicken when done, and add the meat.
Frankly, in over 40 years of catering/cooking, I have never used arugula in anything other than a salad or as a deliberate "bittering" agent in a soup.
It's always a good idea, of course, to "preview" an ingredient before you commit to using it in a recipe. But then, it's one thing when you err on two portions for the home kitchen; another when it's for a couple of hundred servings.