Start by slicing the fennel into wedges and cutting the potatoes into bite-sized chunks. Make sure everything is evenly sized so it cooks at the same rate. I like to rinse the potatoes slightly to remove excess starch.
Place the fennel and potatoes on a baking tray and drizzle with olive oil. Add salt and pepper, then toss everything well to coat evenly. Roast in a preheated oven at 200°C (400°F) until golden and caramelised.
In a small bowl, mix tahini, lemon juice, garlic, and water. Stir until smooth and creamy, adjusting the water as needed. The texture should be pourable but still rich.
Combine chopped parsley, lemon zest, and olive oil in a bowl. Mix gently to keep the herbs fresh and vibrant. This topping adds a bright contrast to the roasted vegetables.
Once the vegetables are caramelised, transfer them to a serving dish. Drizzle generously with tahini cream and finish with gremolata. Serve immediately while warm for the best taste.