3/4 cup quinoa, any color or variety
8 cups (2 quarts) water, plus more as needed
2 tablespoons olive oil
1 medium garlic clove, finely chopped
1 jalapeño, seeded and finely chopped
1/2 pound Yukon Gold potatoes (about 1 large potato), peeled and small dice
1 teaspoon ground cumin
1 teaspoon kosher salt, plus more as needed
1 bunch scallions, thinly sliced (white and light green parts only)
3 cups thinly sliced spinach leaves (from about 1 bunch)
4 ounces feta cheese, small dice (about 1 cup)
1/3 cup coarsely chopped fresh cilantro leaves
Freshly ground black pepper
1 hard-boiled egg, peeled and finely chopped