How to Make It
Toss together spinach, romaine, cucumbers, and radishes in a large bowl.
Stir together shallot, vinegar, and lemon juice in a medium bowl; let stand 5 minutes. Stir in sour cream, and gradually whisk in half-and-half. Stir in chopped mint, salt, and black pepper.
Top spinach mixture with feta cheese; garnish with mint leaves, and serve with dressing.