Step 1

Cook broccolini in a large pot of boiling salted water until bright green and crisp-tender, 5–7 minutes. Drain and transfer to paper towels.

Step 2

Meanwhile, mix tahini, miso, soy sauce, mirin, vinegar, sesame oil, 2 Tbsp. vegetable oil, 1 tsp. honey, and 2 Tbsp. water in a small bowl to combine; season sesame sauce with salt.

Step 3

Cut lemon lengthwise into quarters, then thinly slice crosswise. Toss in a small bowl with remaining 2 Tbsp. vegetable oil and remaining 1 tsp. honey; season lightly with salt.

Step 4

Spread sesame sauce on a platter and arrange broccolini on top. Scatter lemon over; sprinkle with sesame seeds.

Step 5

Do Ahead: Sesame sauce can be made 1 day ahead. Cover and chill. Bring to room temperature before using.