Place lamb, oil, garlic, oregano, mint and lemon juice in a large snap lock bag. Season and rub to coat. Set aside for 10 minutes.
Heat a large non-stick frying pan over medium-high heat and cook lamb, turning, for 4 to 5 minutes, until browned and cooked to your liking. Set meat aside on a plate, cover with foil and rest for 5 minutes.
Meanwhile, heat taco shells or tortillas according to packet directions.
To serve, divide lamb, baby spinach, onion, tomato, cucumber, feta and olives between tacos or tortillas. Serve with tzatziki, mint leaves and lemon wedges
You could also serve these in hard taco shells or for a healthier option in wholemeal pita pockets.
For a Moroccan twist, substitute the oregano and mint with 1 tablespoon Moroccan seasoning, and serve with red capsicum instead of olives and goats cheese instead of feta.
Lamb mince would be a great alternative to diced lamb in this recipe.