Place sliced red onion and hearts of palm salad cuts in a bowl. Add parsley, 3 tbsp. olive oil, and 3 tbsp. lemon juice. Season with salt and pepper. Toss gently until well combined.
Place the desired amount of arugula in each individual bowl. Drizzle lightly with olive oil and lightly season with salt and pepper. Spoon hearts of palm mixture over the top of the arugula. Serve and enjoy!