Rinse parsley and dry with a paper towel. Cut off the thick stems, roughly the bottom 2 inches. Then, finely chop the parsley and remaining stems. You can do this by hand, or use a food processor. I do it by hand.
Transfer to a mixing bowl.
Dice cucumber and tomatoes, add to the bowl of parsley.
Finely chop the red onion and fresh mint and add to the bowl.
Add the juice of one lemon, then salt and pepper to taste. Mix well.
If you want more lemon, add it. I love lemon so I usually add at least 1 1/2 lemon to mine.