Pre-heat the oven to 50°C (top/bottom heat).
Spread the lemon zest on a baking tray. Dry the zest on the medium rail of the oven for about 10 minutes. Remove and allow to cool down.
Roast the fennel seeds in a pan without oil until fragrant. Let cool down.
Grind the fennel, salt and pepper in a mortar until fine. Add the lemon zest and sugar and grind again until fine. Mix with the ginger and garlic.