In a medium bowl, combine the tomatoes, corn, half of the cilantro, the onion, lime juice, 1/4 teaspoon of the cumin, the ketchup, and salt. Set aside.
Prepare the fritters: In a medium saucepan over medium-high heat, combine the broth, chili powder, butter, and remaining salt. Bring to a boil. Add the couscous in a stream. Stir once. Cover and remove from the heat. Set aside until the couscous is tender, 12 to 15 minutes. Transfer to a medium bowl and combine with the egg.
Preheat the oven to 200 degrees F. In a medium skillet over medium-high heat, pour vegetable oil to a depth of 1/2 inch. Heat until a pinch of couscous sizzles instantly. Place the couscous mixture, in 1/3 cup increments, into the skillet. With a spatula, flatten into croquettes 3 to 3 1/2 inches in diameter. Fry until golden brown, 6 to 8 minutes on each side. Transfer to a plate with paper towels to drain. Keep warm in the oven.
In another medium skillet over medium heat, cook the sausage, breaking it up with a fork, until thoroughly cooked, 6 to 8 minutes. With the spatula, transfer the meat to plate lined with paper towels to drain. Set aside.
Spoon some of the salsa onto 4 individual dinner plates. Set a fritter in the center of each plate. Top with equal portions of sausage and additional salsa. Garnish with the remaining cilantro leaves and serve.
Recipe courtesy of Couscous by Kitty Morse, Chronicle Books. Image courtesy of Alison Miksch.