mixed citrus salad with feta and mint

INGREDIENTS

• 3 to 4 tablespoons red onion, cut into tiny bits
• 4 pieces of citrus, preferably a mix of grapefruits and oranges but use what you can get, and what you like to eat (spoiled by the spread at the store, I used 1 pink grapefruit, 1 cara cara and 1 blood orange, and 1 mineola)
• 1 tablespoon red wine vinegar or lemon juice
• 1 teaspoon smooth Dijon mustard
• 1 tablespoon olive oil
• Salt and freshly ground pepper, to taste
• 3 to 4 tablespoons (1.5 ounces) feta cheese, chopped or crumbled
• 1 tablespoon fresh mint, chopped or cut into tiny slivers