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.