Ceviche de pescado mexicano
white fish fillets (such as grouper, mullet, or mackerel), cut into small cubes (1 kg) • lime juice (about 240 ml) • water • salt (7 grams) • firm red tomatoes, diced and seeded (about 500 grams) • medium onion, chopped • green onion with stem, chopped • cilantro, cleaned and chopped • dried oregano (5 ml) • chopped green chile or jalapeño, seeded, to taste • Juice of 3-4 limes • salt to taste •