Heat oil in a large saucepan over medium heat. Add onion and season with salt. Cook, stirring occasionally, for 3-4 minutes or until just softened.
Add spinach, and cook, stirring, for 1-2 minutes or until starting to wilt.
Add rice and stir to coat. Add passata, water and lemon juice. Season, then bring to the boil.
Reduce heat to low, cover and simmer, stirring occasionally, for 20 minutes or until almost all of the liquid has been absorbed and the rice is tender.
Stand, covered, for 10 minutes. Serve with lemon cheeks for squeezing over.
