Step 1 Pulse the cherries in a food processor until coarsely chopped, then place the chopped cherries in a medium bowl. Stir in the onion, lemon juice, balsamic vinegar and tarragon. Season with a pinch each of salt and pepper, or to taste.
Step 2 Gently fold in the yellow pepper. Cover and let stand 15 minutes for the flavors to meld. This makes about 3 cups relish.