3) In a large bowl combine lamb, spring onions, onion powder, oregano, rosemary, garlic powder, cumin, thyme, salt and pepper, to taste. Form meat around skewers, making an oblong sausage shape pressing and securing firmly. Refrigerate 30 minutes.
4) Remove skewers from refrigerator. Brush grill with oil. Grill kebabs until charred on the outside and medium-rare on the inside, turning only once, about three minutes each side. Brush pita lightly with oil, and grill briefly on both sides to warm. Remove lamb kabobs from skewers and place two on each pitta. Drizzle with Tzatziki Sauce to serve.
5) For the tzatziki sauce: Add the yogurt, cucumber, garlic, hot sauce, lemon juice and zest in a food processor and blend until smooth. Season with salt and pepper, and transfer to a bowl. Refrigerate at least one hour before serving.