Before cooking, clean the mussels and clams. I leave them in a bowl of cold water and allow them to sit for at least 20 minutes to get all the sand out. Then use a brush or scrubber (those potato ones are great) and scrub all the shells of any outside dirt.
For the mussels, there's a little "beard" that holds them together, using a pairing knife, pull that out. Leave the shellfish over ice, chilled until ready to use.
Next heat your paella pan and drizzle with olive oil on medium-high heat. Add the chopped onions, and peppers and saute until just tender, about 2-3 minutes.
Then add the chorizo and chopped garlic and and continue cooking for another 1-2 minutes until the garlic is carmelized and chorizo has a nice deep golden color. You may want to turn the sausage so both sides get a good sear.
Next add in the tomatoes with their juices and paprika and saffron. Bring to a gentle simmer and allow the liquid to evaporate slightly so the tomatoes concentrate.
Add the dried rice and toss the rice into the liquid and all the other flavors, making sure everything is coated evenly then use your spatula to spread the rice and everything else evenly around the pan.
Add stock and white wine and bring everything to a simmer for about 20 minutes. Check the pan every so often, making sure the hot spots aren't cooking faster, you may need to turn the pan every so often.
Once the rice is about half way cooked, add the salmon around the pan and continue cooking for another 10 minutes (You may need to cover with foil for even cooking).
Then add the clams and mussels and cook for another 10-12 minutes until they open up. I nestle the shellfish into the liquid making sure it gets enough cooking.
Once all fish is cooked, turn off heat and add peas and garnish with lemon and parsley.