Pre-heat oven to broil and line a broiler pan with foil. Spray with cooking spray.
Toss asparagus well with olive oil, salt and pepper then lay in a single line on pan. Broil on high until caramelized, about 6-7 minutes, tossing once halfway through.
While asparagus is broiling, make tahini sauce. In a small bowl, whisk together tahini, lemon juice/zest, garlic, and salt. Slowly add in the hot water until desired consistency is reached. Serve with warm asparagus.