Heat a large fry pan with a medium heat and add in the olive oil

In the meantime, add the salmon fillets over some paper towels and pat dry, then season with sea salt & black pepper, just on one side, and cut each fillet into 2 evenly sized pieces, for a total of 4 pieces of salmon

Add the pieces of salmon into the hot fry pan, all in a single layer and evenly spaced out, fry for 2 minutes per side, at this point you don't have to fully cook the salmon, then transfer into a dish

Using the same pan with the same heat, add in the chopped onion and garlic, mix continuously, after 3 minutes and the onion is slightly translucent, add in the flour, continue to mix for 1 to 2 minutes, then add in the paprika and oregano, quickly mix together, then add in the milk and vegetable broth, mix continuously

Once you end up with a slightly creamy sauce, about 4 minutes, add in the lemon juice and season with sea salt and black pepper, mix together, then add in the spinach, gently mix it into the sauce until it's lightly wilted, then add the salmon fillets back into the pan, gently flip each one so they're coated in the sauce, lower to a low-medium heat and simmer until the salmon is cooked through, about 2 to 3 minutes

Serve directly out of the pan, enjoy!