Bring a saucepan filled with water to a boil. Add cauliflower, cover, and simmer until barely tender, 2 to 3 minutes. Drain.
Heat 1 teaspoon olive oil in a large skillet over medium heat; cook and stir cauliflower and corn until cauliflower is tender and corn is heated through, about 5 minutes. Stir in sesame seeds, 1 tablespoon honey, turmeric, salt, and black pepper; transfer vegetables to a large bowl.
Whisk parsley, 1/2 cup olive oil, lemon juice, garlic, 1 tablespoon honey, vinegar, Dijon mustard, and soy sauce in a bowl. Season with salt and pepper.
Mix arugula and green onion into cauliflower mixture. Pour parsley dressing over vegetables and toss to combine. Sprinkle oregano over salad. Refrigerate until chilled 20 to 25 minutes.