Put the chicken cubes in a bowl. Add garlic, salt, crushed peppercorns, coriander leaves, lemon juice, egg and tomato ketchup. Let them marinate for half an hour. Place the breadcrumbs in a plate. Take toothpicks and string two chicken cubes on each with a cheese cube between them. Roll them in the breadcrumbs so that they are well covered all around. Dip them in the remaining marinade and once more roll them in the breadcrumbs to double coat. Press lightly so that the breadcrumbs stick firmly. Heat sufficient oil in a kadai till hot. Slide the chicken and cheese fingers and deep fry till golden and crisp. Drain and place on an absorbent paper. To make the sauce mix mayonnaise and tomato ketchup in a bowl. Arrange the chicken and cheese fingers on a serving plate, garnish with a sprig of parsley and serve hot with the sauce.