Ceviche is a great fresh starter and perfect for sharing. It's not strictly a Mexican creation: Peru and Columbia would also claim to have invented it, but the main ingredients are commonly found in Mexico.
Sweet potatoes, or plantain, cut thinly like crisps, are a nice addition with which to scoop up the diced, briefly-marinated fish. I quite like to serve all of the accompaniments on the side so that you can mix in as much, or as little, as you like, to taste.
250-300g mackerel, skinned, boned and cut into approximate 1cm cubes
Juice of 3 limes
1tbsp of soda or sparkling mineral water
1-2tbsp olive oil
Salt and freshly ground white pepper
1 small red onion, very finely diced
1 large green chilli, seeded and finely chopped
2-3tbsp chopped fresh coriander
¼ cucumber, halved lengthways then cut into small dice
2 sweet potatoes, washed
Vegetable or corn oil for deep frying
Preheat about 8cm of oil to 160-180C in a large thick-bottomed saucepan or electric deep-fat fryer.
Meanwhile, slice the sweet potato lengthways, with the skin on, using a mandolin, to the thickness of about one-fifth of a centimetre. Deep fry for 3-4 minutes, or until crisp, turning in the oil with a slotted spoon during cooking, then transfer on to kitchen paper and scatter with a little salt.
Mix all of the ingredients with the mackerel and season to taste.
You can serve the ceviche directly on the sweet potato crisps, or simply put it in a bowl and let your guests help themselves.