In a glass jar, combine olive oil, red wine vinegar, lemon juice, garlic, salt, and black pepper and whisk or shake until combined. Taste and adjust seasonings if necessary. Alternatively, blend until fully incorporated.

Place the hearts of palm “spaghetti” in a mixing bowl. Add mangos, scallions, red onion, and parsley. Drizzle with the marinade and gently toss to coat.