Mince garlic and whisk it together with red wine vinegar, dried oregano, kosher salt, Dijon mustard, and black pepper in a small bowl. Gradually drizzle in olive oil while whisking until emulsified. Set aside.

Rinse farro under cold water in a fine-mesh strainer until clear. Boil salted water, add farro, and cook for 15 to 30 minutes until tender. Drain and cool on a baking sheet.

Wash and dice bell peppers, chop celery, and slice cucumber and red onion. Add sliced pepperoncinis if using.

Combine cooled farro, chopped veggies, and chickpeas in a bowl. Pour vinaigrette over salad and mix well. Adjust seasoning.

Chop iceberg lettuce and radicchio. Store separately in airtight containers until serving.