Halve the Brussels sprouts lengthwise and add to a medium sized bowl. Add olive oil and season with salt and pepper. Toss to coat.
Line a large baking sheet with parchment paper or silicon baking mat. Add the sprouts to the sheet and space them out as much as possible.
Roast for 25 minutes
While the sprouts are roasting, add the tahini sauce ingredients to a small bowl and whisk until smooth. If the sauce is too thick, add water a little bit at a time until it reaches the consistency you like.
Place the roasted sprouts on a serving tray and lightly drizzle with tahini sauce.