Whisk together all marinade ingredients in a small bowl. Reserve 1/3 cup marinade for basting and as a dressing. Place pork in a large, heavy-duty, resealable plastic bag. Add marinade and seal bag. Turn bag several times to coat pork with marinade. Marinate in refrigerator for at least four hours.
Preheat grill to medium-high setting. Slice unpeeled zucchini lengthwise into four long strips. Seed peppers and cut each one in half.
Place pork on a grill rack that has been coated with cooking spray or lightly brushed with oil. Grill meat until it's nicely browned on the outside and just slightly pink in the centre, about 16 minutes. Be careful not to overcook pork.
Add peppers and zucchini for the last eight minutes of cooking time. Turn vegetables once to grill both sides, and baste with some of the reserved marinade.
Remove pork and vegetables from grill and let pork rest for five minutes before slicing.
Meanwhile, slice peppers into thick strips and cut zucchini strips in half crosswise. Place vegetables in a large bowl and add mango, thinly sliced pork, and a bit of reserved marinade. Toss well.
Serve on a bed of baby spinach leaves, if desired. Top with freshly ground black pepper.
Per serving: Calories 275; Total fat 9 g; Saturated fat 2.1 g; Protein 27 g; Carbohydrate 23 g; Fibre 4.1 g; Cholesterol 74 mg; Sodium 449 mg.