Make the pickled red onions, the lemon vinaigrette dressing and the sweet potato croutons (see notes).
Season salmon filets with sea salt and ground pepper, to taste.
Heat oil in a large skillet (a cast-iron works great) over medium-high heat.
Place salmon in pan, skin side up, for about 4 minutes or until the flesh is golden brown.
Turn and cook until salmon is medium-rare; about 4 more minutes.
In a salad bowl, toss greens with sweet potato croutons, pickled red onions, feta and pepitas.
Divide between 2 plates; top salad with salmon and avocado.
Drizzle with lemon vinaigrette dressing and season with additional salt and pepper, to taste.