For the chilli cheese croquettes, place the potatoes and garlic into a pan of salted water and bring to the boil. Cook for 15-18 minutes, or until the potatoes are tender, then drain and return to the pan.
Place the pan back over the heat for a few minutes to drive off any excess moisture from the potatoes, then remove from the heat and mash the potato and garlic well until smooth. Beat in the olive oil, then season with salt and freshly ground black pepper.
Mould a small portion of the mashed potato around a piece of cheese to form a sausage shape about 7cm x 3cm/3in x 1½in. Repeat with the remaining cheese and mashed potato until all are used up.
In a large bowl, mix the panko crumbs and chilli flakes together.
Dust the potato and cheese parcels in the flour, dip into the beaten egg and roll in the panko and chilli flake mixture until well coated. Place onto a tray and cover with cling film, then chill in the fridge for 30 minutes.
Meanwhile, for the tomato cumin sauce, heat the olive oil in a pan and fry the onion, garlic and chilli for 2-3 minutes, or until softened. Add the ground cumin and cook for a further minute, then add the tomatoes and bring to a gentle simmer. Cook for 20 minutes, or until the mixture has reduced and thickened to a sauce consistency. Season, to taste, with sugar, salt and freshly ground black pepper.
For the salad, place the rocket and watercress leaves into a bowl and toss together. Drizzle the extra virgin olive oil and lemon juice around the inside edge of the bowl, then season with salt and freshly ground black pepper. Toss the salad to coat in the olive oil and lemon juice.
For the chilli cheese croquettes, half-fill a deep, heavy-based pan with vegetable oil and heat to 170C/325F, checking the temperature with a digital thermometer (CAUTION: hot oil can be dangerous. Do not leave unattended).
Remove the croquettes from the fridge and fry them, in small batches, in the oil for 2-3 minutes, or until golden-brown and crisp. Remove with a slotted spoon and drain on kitchen paper.
To serve, place three croquettes into the centre of each serving plate. Spoon the tomato cumin sauce into small dipping bowls or ramekins and place alongside the croquettes. Arrange the salad alongside and serve.