Add yellow onions...saute 5-8 minutes until cooked through.
Add garlic and tumeric, saute for one minute.
Add rice and cook for 2 minutes, stirring to coat all of the rice with the onion, spice mixture.
Add cubed chicken thighs. Stir to combine.
In blender, place jar of roasted red peppers (including their liquid) and smoked paprika. Blend until pureed. Pour mixture into skillet. Stir to combine and bring to boil over medium heat.
Add 1 cup of hot chicken stock and 2 teaspoons of salt. Stir to combine and then cook uncovered for about 8 minutes, stirring occasionally until most of the stock has absorbed.
Continue to cook paella without a lid, adding hot chicken stock one or 2 cups at a time, whenever you see that the stock has mostly absorbed...do this for about 20 more minutes.
Add roasted vegetables to paella and some more stock. Stir gently.
Once the rice is tender (will vary from rice to rice) place fresh mussels, valve side down into rice mixture. Cover with lid and cook for another 5 - 8 minutes until mussels open.
Discard any mussels that did not open.
Sprinkle the top with sliced scallions.
Serve in large bowls with shredded Manchego cheese on the side.