Prepare rice in boiling salted water according to package instructions and let it cool completely. Defrost the peas. Drain the tuna in a sieve, collecting the oil. Peel and grate celery. Peel and finely chop the ginger. Peel and finely chop the onion.
Heat the tuna oil in a large frying pan and fry the rice well. Add onion, ginger and celery and fry over medium heat for about 8 minutes. Wash the chives, shake dry and cut into fine rolls. Add tuna and peas to the rice just before serving, season with soy sauce. Sprinkle with chives.