Make the salad dressing. Place ⅓ cup extra virgin olive oil, 3 Tbsp red wine vinegar, 1 clove minced garlic, 1 tsp oregano, 1 tsp Dijon, 1 tsp Kosher salt, ½ lemon zested, and 1 Tbsp fresh lemon juice in a bowl. Whisk to combine, then set aside. Alternatively, place all dressing ingredients in a mason jar, then seal rightly and shake well.
Toast the croutons. Preheat oven to 375°F/190°C. Place bread cubes on a rimmed baking sheet, then drizzle with 2 Tbsp extra virgin olive oil and ½ tsp Kosher salt. Bake until crispy, about 5-7 minutes. Set aside.
Salt the tomatoes. Place chopped tomatoes in a large bowl, then season with remaining ½ tsp Kosher salt. Let sit for 10 minutes (or while you prepare the rest of the salad).
Cook the salami. Heat 1 Tbsp neutral oil in a medium skillet over medium heat. When hot, add diced salami. Cook until crisp all over, about 3-4 minutes, stirring often. Drain on a paper towel lined plate or bowl.
Toss the salad. Combine all salad ingredients in a large bowl: toasted croutons, seasoned chopped tomatoes, crispy salami, sliced red onion, ripped basil, and fresh mozzarella. Drizzle the dressing on top, then toss to evenly coat.
Rest 30 minutes. Allow the panzanella salad to rest for at least 30 minutes or up to 1-2 hours max. Sprinkle with flaky sea salt, then serve!