Pat the salmon fillet dry with a paper towel and season both sides with half of the sea salt and black pepper.
Heat the olive oil in a medium non-stick skillet over medium-high heat until shimmering.
Place the salmon in the pan skin-side down and press gently; sear for 4 to 5 minutes until the skin is golden and crispy.
Flip the salmon carefully and cook for an additional 2 to 3 minutes until the internal temperature reaches 145°F.
Remove the salmon from the pan and set aside; in the same skillet, add the minced garlic and sauté for 30 seconds until fragrant.
Add the baby spinach to the skillet and toss until just wilted, then remove from heat.
In a small bowl, toss the sliced cucumbers with the lemon juice, chopped fresh dill, and the remaining salt and pepper.
Plate the wilted spinach, top with the pan-seared salmon, and serve the refreshing cucumber salad on the side.