Pork Souvlaki with Fennel Salad and Tzatziki

Name: Pork Souvlaki with Fennel Salad and Tzatziki
Ingredients: 2 pounds pork shoulder, cubed; 3 tablespoons garlic, grated; 1/2 cup lemon juice; 1/2 cup finishing olive oil; 3 tablespoons fresh oregano; 1 tablespoon fennel pollen; Kosher salt; 3 cups shaved fennel; 2 cups shaved celery plus leaves; 2 tablespoons shaved Fresno chiles; 1/4 cup lemon juice; 2 tablespoons picked fresh parsley leaves; 2 tablespoons olive oil, plus more to drizzle bread with; Kosher salt and freshly ground black pepper; 2 cups whole milk Greek yogurt; 3 Persian cucumbers, halved and thinly sliced; 1 Fresno, trimmed, seeded and finely diced; 1 clove garlic, grated; Pita bread, toasted or grilled, and quartered for serving