Preheat the oven to 200°C, fan 180°C, gas mark 6.
Heat half a tablespoon of the olive oil in a frying pan, add the steak mince and break up with a fork. Cook over a high heat for 2-3 minutes, until browned and no pink remains. Stir in the herb seasoning then transfer to a plate and set aside.
Place the peppers cut side up on a baking tray and bake in the oven for 20 minutes. Remove and set aside.
Meanwhile, discard any remaining fat from the pan then add the rest of the olive oil. Add the onion and cook over a medium heat for 5 minutes until softened. Stir in the garlic and rice, cook for a minute.
Add the lemon zest and juice then gradually pour in the stock, stirring at regular intervals until absorbed. This should take 15 minutes.
Stir in the courgette and cook for a further 3-4 minutes until both the rice and courgette are tender. Remove from the heat, stir in the pesto and gently fold through the tomatoes.
Divide the risotto equally between the peppers, then spoon over the mince. Top with the mozzarella and season.
Return to the oven and bake for 5 minutes until the peppers are cooked through.