pickle onions:

1. In a small bowl, whisk sherry vinegar, water, salt and sugar together until dissolved. Mix in onion and refrigerate at least 30 minutes, if possible, to soften the bite of the onion.

cook squash, grapes, and farro:

1. While onions pickle, preheat oven to 400°F.
2. On an aluminum foil-lined baking sheet, add butternut squash cubes, 2 tbsp olive oil and season with salt and freshly ground black pepper. Toss squash to coat evenly and roast in the oven, 30- 40 minutes. Halfway through roasting, flip squash with a spatula, and continue to cook until soft and beginning to brown.
3. Remove from oven and transfer squash to a large bowl.
4. On the same baking sheet, toss grapes with 1/2 tsp olive oil and season with salt and freshly ground pepper. Roast grapes, shaking the pan once or twice to roll them around, until the grapes begin to burst and shrivel, 8- 10 minutes. Remove from oven and combine with squash.
5. While the squash and grapes are roasting, cook farro in a large pot of simmering salted water until grains are tender but chewy (follow directions on the package for exact cooking times). Drain, cool slightly, then transfer to bowl with squash and grapes.

make dressing + assemble butternut squash salad:

1. Using a fork, remove pickled onions from vinegar brine and place in large bowl with squash, grapes and farro, along with pecans and parsley. Add 3 tbsp vinegar brine and 3 tbsp olive oil to mixture, toss, taste and add more brine, olive oil, salt or pepper to taste. When ready to serve, sprinkle feta crumbles over the salad, toss, and enjoy.