In a resealable plastic bag or lidded container, put the lamb fillets, garlic, oregano, olive oil and black pepper. Seal and toss well to ensure the lamb is well covered with the marinade. Refrigerate for 2-3 hours.
Toss the aubergine pieces in olive oil and pan-fry in a hot pan until they are well browned and softened. Place in a bowl with the cherry tomatoes, spring onions, sundried tomatoes, basil and vinaigrette. Season with pepper and salt and set aside.
Heat a frying pan or grill pan and, when hot, add the lamb fillets and cook over a high heat, turning to brown evenly. Cook only 4-5 minutes until the fillets are medium rare. Remove from the pan and stand for 2-3 minutes before slicing thickly.
Toss the lamb fillets and any juices that have collected through the salad.
Serve on toasted focaccia or ciabatta bread with baby salad leaves. Accompany with Roasted Garlic Aioli if wished (recipe below).
Roasted Garlic Aioli
Drizzle 2 bulbs of garlic with olive oil and wrap in foil. Bake at 180°C for 1 hour or until a skewer can easily be inserted and the pulp is soft. Remove, unwrap and cool. Cut in half horizontally and squeeze the soft, cooked pulp into a bowl. Season with the juice of ½ lemon, salt and pepper, and then whisk in ½ cup olive oil to make a thick paste.