In a large skillet, heat 1 tbsp of vegetable oil, over medium-high heat.
Add finely chopped onion and garlic, and sauté for 2 minutes on medium-high heat.
Add finely chopped red bell peppers, parsley, saffron & smoked paprika, continue sauté on medium heat for another 5 minutes. Season with salt & pepper and stir occasionally.
Move all the vegetables on the side of a skillet & saute seasoned chicken thighs and mergues sausages in the same skillet. Approximately 2 minutes each side.
Remove chicken thighs & mergues sausages on a small plate and set aside.
Add to the skillet chicken stock, washed rice & frozen corn with green peas. Stir all to combine. (Optional; now you can add diced tomatoes as well).
Bring the rice to the gentle boil and immerse gently chicken thighs, mergues sausages, shrimps, scallops and mussels inside the rice. Cover the skillet with lid & let the paella cook on medium low heat for 15 minutes. Do not open the lid.
After 15 minutes all the liquid should have evaporated. Check for unopened mussels, and discard those immediately. Keep only opened mussels.
Once paella is cooked, sprinkle with fresh chopped parsley and drizzle with fresh lemon juice. Serve immediately!