Before cooking, peel and wash the onions and garlic cloves. If the squid and shrimp are frozen, then defrost them and rinse them in cold water. Shrimp are needed without shell, so they must be cleaned first. Cut the onions and garlic into small cubes. Cut the squid carcass into small thin strips. Drain excess liquid from canned octopus. Wash and finely chop the cilantro for serving.
Cook the rice. Boil water in a saucepan, add salt and add rice. Stirring, cook the rice until tender, then drain in a fine sieve or colander and rinse with cold water.
Fry the seafood. Heat vegetable oil in a wok over medium heat. Add squid, shrimp and octopus to it and fry for 5-6 minutes, stirring constantly. Remove seafood from pan and temporarily transfer to a plate.
Fry vegetables and rice. In the same frying pan where the seafood was fried, place the chopped onions and garlic and, stirring, fry for 2-3 minutes. Then add boiled rice to the vegetables, stir so that there are no lumps. Stirring vigorously, fry the rice for 4-5 minutes, and then add squid, shrimp and octopus to it and pepper. Add soy sauce to the seafood rice and mix well again.
Place seafood fried rice on serving plates, drizzle with lemon juice and sprinkle with finely chopped fresh cilantro.