Halve the chicken breast fillets lengthways and place in an ovenproof dish.
Clean the leek and cut into rings.
Peel the mango and cut into wedges.
Spread the leek rings and mango wedges over the chicken fillets.
Peel the ginger and press through a garlic press.
Mix the ginger, coconut milk, curry, and sambal oelek in a bowl, then season with salt and pepper.
Pour the sauce over the chicken and vegetables.
Bake in a preheated oven at 220°C / 428°F (conventional) or 180°C / 356°F (convection) for 40–50 minutes until the chicken reaches 74°C / 165°F internally.