Season chicken with salt and pepper and brown in a sprayed frying pan for 3 minutes per side.
Remove chicken and sauté sliced onion and garlic until softened.
Add tomatoes, purée, oregano, olives, and 300ml water, then boil for 5 minutes.
Simmer chicken in the sauce for 10 minutes until cooked through.
Top chicken with sliced mozzarella and grill until melted.
Sauté the second onion and garlic in a small saucepan.
Process beans with 100ml water and seasoning, then blend with the sautéed onion and garlic.
Heat the bean purée in a pan, add lemon juice, and serve with the chicken.