Heat the olive oil over medium-low heat in your skillet until it shimmers gently, giving off a fragrant aroma.
Add the thinly sliced garlic to the hot oil, stirring gently. Let it sizzle softly, stirring occasionally, until it turns translucent and fragrant, about 1-2 minutes.
Once the garlic is golden and aromatic, add the fresh spinach to the skillet, a handful at a time if needed. Use tongs or a spoon to toss the leaves into the garlic oil, letting them wilt and reduce in volume.
Cook the spinach, stirring constantly, until it is wilted and vibrant green, about 2-3 minutes. The leaves should be tender but still bright and glossy.
Season the greens with a pinch of sea salt and squeeze in the lemon juice, tossing everything to combine and brighten the flavors.
Remove the skillet from heat and transfer the sautéed spinach to a serving dish. Finish with a sprinkle of freshly cracked black pepper and an extra drizzle of olive oil if desired.