For the salmon: Preheat the oven to broil. Line a baking sheet with aluminum foil.
Place the salmon skin-side down on the baking sheet and sprinkle with the red pepper ﬂakes, salt, and pepper. Arrange the lemon slices over the ﬁsh. Broil for 10 minutes, until the salmon is cooked through.
For the vinaigrette: Meanwhile, combine the oil, vinegar, mustard, and shallot in a jar with a lid and shake. Divide the mixed greens among 4 plates and drizzle some of the vinaigrette over the greens.
Place a salmon ﬁllet on each plate and serve, garnished with fresh dill.
I like to make salmon on Sunday to eat later in the week. Put in a sealed container and store in the fridge for up to 3 days.