Mince garlic; place in a large bowl. Add oil, lemon juice, sauce mix, pepper, and topper blend, if using. Whisk to combine.
Slice peppers and onion; add to bowl along with cooked potatoes and sausage. Using a spatula, toss until well coated. Place on prepared pan, spreading out in a single layer as best you can. Roast 10 min.
Add prawns to bowl and stir gently to coat with any remaining oil mixture. Set aside.
Add prawns and roast an additional 12–15 min, or until prawns are cooked and sizzling. Top with lemon slices, if desired.
Per serving: Calories 250, Fat 16 g (Saturated 3.5 g, Trans 0 g), Cholesterol 60 mg, Sodium 440 mg, Carbohydrate 15 g (Fibre 2 g, Sugars 2 g), Protein 11 g.
Swap chorizo sausage with cured sausage of your choice.