Make the pasta: Heat 3 quarts water in a large pot. As water comes to boil, heat oil in a large sauté pan, and sauté onion on medium-low until soft. Stir in cumin. Add merguez, increase heat to medium and cook, using two forks to break up the sausage and stirring all the while, until the meat is nubbly and no longer looks raw. Stir in sun-dried tomatoes, olives and 2 tablespoons of the pesto. Reduce heat to low.