In a large pot, add the water, lemon juice, and salt. Bring it to a boil.
Take the pot off the stovetop and add the couscous and put the lid back on. Let it soak for 5 minutes.
Meanwhile, peel the onions, cut them in half, and slice them into half-rings. Chop the parsley.
Heat a large pan with the canola oil and place the onion rings in there. Cook them on medium-high heat while stirring constantly, and keep them on the heat until they're soft and get a nice golden color.
To the couscous, add the onions and chopped parsley. Give it a good mix. Serve either warm or cold!