Prepare the fruits and vegetables: Peel the mangoes and cut into thin julienne strips. Wash and julienne the cucumber (peeling is optional). Thinly slice the red onion.
Make the dressing: In a small bowl, whisk together lime juice, rice vinegar, sesame oil, honey (or maple syrup), and salt until well combined.
Combine ingredients: In a large serving bowl, gently toss the mango strips, cucumber strips, and sliced red onion.
Dress the salad: Pour the dressing over the mango-cucumber mixture and toss gently to coat all ingredients evenly.
Add fresh herbs: Sprinkle the chopped mint leaves over the salad and give it one final gentle toss.
Garnish and serve: Top with crushed peanuts and minced Thai chili if desired. Serve immediately for best texture and flavor.
