Combine Dry Ingredients: In a small bowl, whisk together the Dijon mustard, finely grated garlic clove, Italian seasoning, kosher salt, and freshly ground black pepper until well blended.
Add Vinegar: Pour in the red wine vinegar and stir to combine with the dry mixture for about 30 seconds.
Whisk in Oil: Slowly drizzle in the extra-virgin olive oil while whisking constantly to emulsify the vinaigrette, about 1 to 2 minutes. If desired, taste and add a touch of honey to balance the acidity.
Prepare Lettuce: Chop the romaine lettuce into bite-sized pieces and place in a large salad bowl.
Add Radicchio: Slice or dice the radicchio and add it to the bowl with the romaine.
Prep Vegetables: Halve the cherry tomatoes if desired, dice the red onion and rinse under cold water, then wrap in a paper towel and squeeze gently to remove excess moisture, and slice the pepperoncini peppers and Kalamata olives.
Add Vegetables: To the bowl of chopped romaine and radicchio, add the cherry tomatoes, diced red onion, sliced pepperoncini peppers, and sliced Kalamata olives.
Layer the Proteins: Scatter the fresh mozzarella pearls and sliced salami evenly over the vegetables.
Dress the Salad: Give the vinaigrette a final whisk to ensure it's well emulsified, then drizzle it over the salad and toss gently but thoroughly until all ingredients are coated and evenly distributed, about 1 to 2 minutes.
Garnish and Serve: Top with freshly grated Parmesan cheese and chopped fresh parsley, then adjust salt and pepper to taste and serve immediately.