When simmering the paella, should I cover the pan with a lid?

I’ve seen paella made both uncovered and covered. You usually cover it when there is meat or seafood that’s not cooking as quickly as the rice. So use your judgment. If the rice is cooking quickly and the vegetables are still raw, cover it. But if you precook the vegetables as the writer suggested, and you cook the paella low and slow, the vegetables will warm as the rice cooks and you shouldn’t have to cover it.