1.Make the labne. Line a sieve with muslin; place sieve over a bowl or jug. Stir salt into yogurt. Spoon the yogurt mixture into the sieve. Cover, refrigerate for 24 hours or until thick. Discard liquid. Roll tablespoons of yogurt into balls. Place into a small container; add rind. Pour in enough oil to cover balls. Cover; refrigerate until serving.
2.Make dukkah. Preheat oven to 180°C/350°F. Spread nuts on an oven tray and sesame seeds on a separate oven tray. Roast nuts and seeds about 10 minutes or until toasted; cool. Meanwhile, dry-fry coriander and cumin seeds in small frying pan, stirring, until fragrant. Cool. Grind coriander and cumin seeds in a mortar and pestle or spice grinder. Process nuts until chopped finely. Combine nuts and all the seeds in a medium bowl; stir in salt and pepper. Store in an airtight container.
3.Heat oil in large frying pan; cook sausages until browned all over and cooked through.
4.Meanwhile, thickly slice tomatoes. Peel and thinly slice onion. Trim rocket. Combine tomato, onion, extra oil and juice in medium bowl; season to taste.
5.Serve sausages with tomato salad, rocket, labne and dukkah. Sprinkle labne with sumac.
Dukkah can be made 2 weeks ahead. Store in an airtight container in a cool, dry place. Sprinkle leftover dukkah on grilled lamb, or serve with olive oil and bread for dipping. Labne can be made 3 days ahead; keep refrigerated. You need to begin this recipe a day ahead.