Whisk together olive oil, mustard, lemon juice, zest, red pepper flakes, salt, and pepper until emulsified.
Add sliced beets and pink beans. Toss gently to coat.
Fold in walnuts and chopped mint. Adjust seasoning to taste.
Chill 30 minutes if desired.
Add feta just before serving and toss lightly.
Notes
Storage Tips: Keeps 2–3 days in the fridge, add feta just before serving.Notes: Substitute kidney or white beans as desired. Toast walnuts for extra flavor. Vegetarian, gluten-free, high-protein. Nutrition facts are automatically calculated and should be considered estimates.