Cook farro according to package instructions. Drain.
Thinly sliced radishes into rounds. Cut onions into ~1 ½” chunks.
Heat oil on medium high in a pan. Sauté onion for 1-2 minutes until starting to turn translucent.
Add asparagus and fava beans. Continue to cook for about 1 minutes until just pierced with a fork.
Remove from heat and toss in radish, farro, mint, salt, and pepper.
Add lemon juice to taste. Serve. Refrigerates well for lunch the next day.