Pre-heat the oven to 200°C (400°F). Line a baking sheet with parchment paper.
Toss the sweet potato with some oil and season with salt and pepper. Roast for 20-25 minutes until tender. Remove from the oven and let cool slightly.
While the potatoes are roasting, prepare the dressing. In a small bowl, mash the garlic with some salt and pepper until you get a smooth paste.
Add the lemon juice, tahini and miso and mix together. Add the water and olive oil whisk to combine. Add more water to achieve the desired consistency.
Assemble the salad while the potatoes are still warm, and enjoy!