Preheat oven to 450 degrees and place washed and dried asparagus spears on a baking sheet. Place in oven and bake for 10 minutes until bright green and tender. They may brown in some spots, this is good.
While cooking asparagus, toast sesame seeds in a skillet on LOW heat (they burn easily). Stir them pretty continuously, in five to ten minutes they will start to smell toasty, and be browning slightly. Take them off heat and set them aside.
When asparagus is done place on a wide plate and drizzle tahini and lemon juice over top. Toss them to coat. Sprinkle with salt and sesame seeds and toss again. Sprinkle with freshly ground black pepper and serve immediately.