Preheat the oven to 400° F. Arrange the brussels on a large baking sheet. Try to keep them from touching each other so they get crispier. You can also use two sheets if needed. Drizzle with olive oil, salt and pepper and stir to coat well.
Put in the oven and roast for 25 minutes. Remove from the oven, flip the brussels so their opposite side browns. Place back into oven for another 15 minutes.
While the brussels are roasting make the sauce. Put salt, garlic clove, and cilantro into a food processor or high speed blender and process for 20 seconds. Add the remaining ingredients and process for an additional 30 seconds. Scrape down the sides and process until smooth. Taste and add more salt if needed.
Remove the brussels, arrange on a plate, and drizzle with the tahini sauce and a little extra chopped parsley.