Heat the oil in a saucepan over medium heat and mince the onion and pepper.
Sautee the onion and pepper in the oil for 5 minutes to soften.
Add the broth, salt and basil and bring to a boil.
Slice the zucchini and add it and the tortellini to the sauce pan. Cook for 8-10 minutes or as directed on the tortellini package.
Halve the cherry tomatoes.
Remove the soup from the heat and stir in the cherry tomatoes and lemon juice. Let rest 5 minutes before serving, and sprinkle with Parmesean cheese if desired.