1.Place diced onion in a small bowl and cover with cold water. Let sit for 10 minutes, then drain. Pat down with paper towels if needed. Set aside.
2.Combine the remaining ingredients in a medium sized bowl and toss well.
3.Add the onions and stir gently to combine.
4.Taste and adjust seasoning with more lemon, salt, and pepper, if necessary.
5.Cover and refrigerate until ready to serve. Best if chilled at least 1 hour.
6.Toss again before serving. Enjoy the freshness!