Heat the oil in the paella pan and cook well the meat.
Add onion, green beans, garlic, and red bell pepper strips. Keep cooking until the vegetables are soft.
Add the tomato puree and the paprika and wait for the tomato puree to reduce a little before the next step.
Now scatter all the ingredients very well because once you add the rice, you can't move it.
Scatter the rice uniformly all over the pan, and add the broth carefully. Make sure it's well distributed all over the paella.
From now on, you can't touch the rice. You can't move it.
Add salt to the broth and season with saffron. While the rice is cooking, the seafood too.
You can arrange the seafood in any way you want to make it more appealing. I like to put the mussels in the center and the shrimp on the sides.
If you use paella rice, you'll notice that it'll grow more than double its size while cooking.
The paella is ready when there is no broth left to absorb, and the rice expands. Keep an eye on the paella because it can burn. So, it's better to taste when there is little broth left in the pan. It'll help to check if the rice is done.
And once is done, serve and enjoy!