Combine quinoa and broth in a medium saucepan. Bring to a boil over high heat. Reduce heat; simmer gently 10 minutes.
Stir in lima beans; continue to simmer 5 to 6 minutes or until liquid is absorbed.
Meanwhile, cut zucchini lengthwise in half. Cut out and discard seeds. Using a sharp paring knife, cut out flesh leaving a 1/3-inch-thick shell.
Chop flesh and set aside. Place hollowed chayote halves in microwave-safe dish.
Cover with vented plastic wrap and cook at high power 5 to 8 minutes or until crisp-tender.
Heat a large nonstick skillet over medium-high heat. Add oil, then chopped squash pulp; stir-fry 2 minutes.
Add salsa; simmer 3 minutes or until squash is tender. Stir ½ cup of salsa mixture into quinoa mixture.
Arrange cooked squash halves, cut side up on four serving plates; sprinkle with salt. Mound remaining salsa mixture into the squash halves.
Spoon quinoa mixture onto and around squash; top with cheese and cilantro. Sprinkle 1 tablespoon of pumpkin or sunflower seeds over each serving, if desired.