Wash the mixed greens thoroughly and pat dry.
In a large salad bowl, combine the mixed greens.
Add the halved cherry tomatoes to the bowl.
Slice the cucumber and radish, then add them to the salad.
Thinly slice the red onion and incorporate it into the mixture.
Crumble the feta cheese over the top of the salad.
In a small bowl, whisk together the lemon juice and olive oil.
Drizzle the dressing over the salad, ensuring even coverage.
Season with salt and pepper to taste.
Gently toss the salad until all ingredients are combined.