Grate tomatoes into a bowl using a box grater; discard tomato skins.
Heat vegetable oil in a heavy pan over medium-high heat and cook onion until softened, stirring often, about 5 minutes. Stir garlic into onion and cook for about 1 minute.
Stir rice into onion mixture and cook, stirring often, until rice is lightly toasted, about 3 more minutes. Stir grated tomato, chicken stock and tomato passata into the rice. Bring mixture to the boil.
Mix in chilli pepper, coriander and salt; reduce heat to low. Cover pan and simmer until rice has absorbed the liquid, about 15 minutes. Do not lift the lid while the rice is cooking.
Turn off heat and let rice stand covered for 8 minutes. Fluff with a fork before transferring rice to a serving dish.