Warm the olive oil in a large skillet with a lid over medium heat. Stir in the sliced garlic and red pepper flakes, allowing them to sizzle and release their aroma for about 30 seconds.
Add the broccolini to the skillet, sprinkling it with sea salt. Toss gently to ensure even coating with the infused oil and seasonings.
Let the broccolini cook, stirring occasionally, for about 2 minutes. Pour in the water, then cover the skillet with the lid. Lower the heat and allow the broccolini to steam gently for 3 to 5 minutes, tossing intermittently, until the stems are tender and the color has deepened to a vibrant green.
Once cooked to perfection, remove the skillet from the heat. Drizzle the broccolini with fresh lemon juice, tossing lightly to coat. Taste and adjust the seasoning with additional sea salt if needed. Serve immediately for the best flavor and texture.