Slice the chicken breast lengthwise into about 4 thin strips.
In a small bowl, whisk together the lemon juice, olive oil, cumin, salt and pepper for the marinade. Add the chicken and toss to combine. Leave to rest for at least 10 minutes if you have time).
Thread the chicken accordion-style onto 2 metal skewers (2 chicken strips per skewer).
Preheat a BBQ or grill pan to medium-high then grill the chicken 3-4 minutes per side, until cooked through.
Meanwhile, combine all the sauce ingredients in a bowl and whisk together until smooth. Add hot water a teaspoon at a time to thin the sauce, if needed.
Let the chicken rest for 5 minutes before serving. Serve on top of leaves, if desired, and drizzle with the sauce.