Pilafs require flexibility in the kitchen. Sometimes they need more cooking liquid; sometimes they need less. So watch this pilaf as it cooks.
In a large saucepan, heat the olive oil over medium-high heat until it shimmers. Add the onions and cook, stirring occasionally, until soft and translucent, about 15 minutes. Add the quinoa, 1/2 teaspoon salt and 1/4 teaspoon pepper. Cook while stirring until the quinoa toasts and begins to pop, about 2 minutes. Add the stock and bring to a boil. Stir, then cover, reduce the heat to low and simmer for 20 minutes.
Remove the lid and taste the quinoa to see if it is done. If not, check if there is still liquid in the pan. If so, cover and cook another 5 minutes, or until tender. If not, add a splash of stock and cook until tender. Fluff the quinoa with a fork, then add the pecans. Season to taste and serve.