Use silken tofu, not firm — it's what gives the vegan "egg" cream its smooth, pourable texture, so blend it until completely silky with no grain left. Lemons vary a lot, so taste the soup at the end and add extra lemon juice or salt as needed. Leftovers keep in the fridge for up to 3 days; the rice keeps absorbing liquid, so loosen the soup with a splash of broth when reheating.