Toast quinoa in a large dry skillet over medium heat, stirring often, until it crackles and becomes aromatic, 3 to 5 minutes. Transfer to a fine sieve and rinse thoroughly.
Heat oil in a large saucepan over medium heat. Add onion and cook, stirring often, until softened, 2 to 3 minutes. Add chiles and garlic; cook, stirring, for 30 seconds. Add the quinoa and broth; bring to a simmer. Reduce heat to maintain a gentle simmer, cover and cook until the quinoa is tender and most of the liquid has been absorbed, 20 to 25 minutes.
Add pepitas, cilantro, scallions, lime juice and salt to the quinoa; mix gently and fluff with a fork.
Tips: Notes: Quinoa, a delicately flavored grain that was a staple in the ancient Incas’ diet, is available in most natural-foods stores and the natural-foods sections of many supermarkets. Toasting the grain before cooking enhances the flavor, and rinsing removes any residue of saponin, quinoa’s natural, bitter protective coating.
Hulled pumpkin seeds, also known as pepitas, are dusky green and have a delicate nutty flavor. They can be found in the health-food or bulk sections of many supermarkets.
To toast nuts & seeds on the stovetop: Toast in a small dry skillet over medium-low heat, stirring constantly, until fragrant and lightly browned, 3 to 5 minutes.