Cut 12 ounces chicken sausage into ½-inch thick rounds and thinly slice ½ small red onion. Place both in a 3 ½-quart straight-sided skillet or Dutch oven. Finely grate the zest of 1 large lemon (reserve the zested lemon) into the skillet. Add 4 cups water, 1 pound dried orzo, 1 jar marinated artichoke hearts and its liquid, 1 tablespoon olive oil, 2 teaspoons kosher salt, and ¼ teaspoon black pepper.
Bring to a boil over high heat. Boil, stirring frequently so the orzo doesn’t stick, until the orzo is al dente and the liquid has nearly evaporated, 8 to 10 minutes. Halve the lemon and squeeze the juice into the skillet. Gently stir before serving.
