This easy dish is best eaten in a bowl with the tender pearls of coucous serving as a bed for the ribbons of chard and chunks of chorizo — or you can jumble them all up together, the choice is yours.
Heat a large pan over medium-high heat, when hot, add the chorizo and stir, breaking up the meat with a wooden spoon. Continue to cook until browned all over and mostly cooked through, about 10 minutes. Remove and set aside.
In the same pan, add the olive oil and then the onion. Stir until softened, about 4-5 minutes. Add the chard stems to the pan first, cooking for about 1-2 minutes until softened. Then add the leaves, tossing to combine all the pieces with the oil and onions. Add the water and partially cover with a lid, lowering the heat to medium. Stir occasionally and cook until wilted and tender, about 6-8 minutes.
Add the chorizo to the pan, stir to combine and cook for about 3-4 minutes more until warmed through. Season with salt and pepper and serve over pearled couscous.