Whisk lime juice, lime zest, oil and mint in large shallow dish until combined. Season with salt to taste.
Add the cucumber and mango and gently toss to coat. Chill and marinate for at least 30 minutes to allow the flavors to develop.
When ready to serve, thread the cucumber and mango pieces onto skewers in an alternating fashion. Sprinkle with extra lime zest, fresh mint and sea salt and serve garnished with cut limes on the side.