Preheat the oven to 200°C. Place the sweet potatoes on a large baking tray. Season with 15ml Robertsons Steak and Chops spice and drizzle with 15 ml cooking oil. Roast in the oven for 25-30 minutes, turning ones halfway cooking time until golden brown
Combine the remaining cooking oil, remaining Robertsons Steak and Chops spice and rub the steak with the spice rub.
Preheat a grill pan over medium high heat. Grill the steak for 5 minutes on each side or until golden brown and cooked to your liking. Set the steak aside for 5 minutes before slicing.
Slice the steak into thin strips. Assemble the Gatsby by layering tomatoes, cucumber, red onion, lettuce, cheddar cheese roasted sweet potato chips, steak on top of each other. Drizzle with mayonnaise and slice into pieces.