Salmon Cakes With Lemon, Dill, And Homemade Dijon Mayonnaise

Ingredients

• 1 large egg yolk
• 2 tablespoons dijon mustard
• 1 tablespoon (or more) fresh lemon juice
• 1/2 cup vegetable or olive oil
• 1 teaspoon finely chopped fresh dill
• kosher salt
• 3/4 pound salmon fillet, preferably sockeye (previously frozen is fine)
• vegetable or olive oil (for brushing and cooking)
• 1 1/2 pounds russet potatoes, peeled, cut into 2-inch chunks
• 1 teaspoon kosher salt plus more for seasoning
• 1 large egg
• 1 large egg yolk
• 2 tablespoons finely chopped fresh dill
• 2 scallions, thinly sliced
• 2 teaspoons lemon zest
• freshly ground black pepper or crushed red pepper flakes (optional)