In a small bowl, whisk together olive oil, lemon juice, minced garlic, Dijon mustard, and red pepper flakes. Add salt and pepper to taste. Let dressing stand for about 20-30 minutes.

In a large mixing bowl, combine drained quartered artichoke hearts, rinsed and drained white beans, diced red onion, and thinly sliced celery. Toss in chopped oregano.

Pour the dressing over the salad ingredients. Toss gently to combine ensuring even coating.

Optionally, refrigerate the salad for up to 24 hours to enhance flavors. Remove from fridge 30 minutes before serving to bring to room temperature.