Heat the oil in a saucepan. Add the scallions and garlic. Stir in the cumin and cook for 1 minute. Add the stock and bring to a boil.
Remove the pan from the heat, stir in the couscous, cover the pan and let stand for 10 minutes, until the couscous has swelled and all the liquids have been absorbed. If you are using instant couscous, follow the package instructions.
Scrape the couscous into a bowl. Stir in tomatoes, parsley, mint, chile and lemon juice. Season with salt and pepper. If possible , set aside for up to an hour, to allow flavors to develop fully.
To serve, line a bowl with lettuce leaves and spoon the couscous salad over the top. Sprinkle the toasted pine nuts and grated lemon rind over the top to garnish.