With the rack in the middle position, preheat the oven to 170 °C (325 °F).
Spread the rhubarb slices in a 33 x 23 cm (13 x 9-inch) baking dish and sprinkle with the sugar. Drizzle with the lemon juice, and top with the lemon slices. Bake for 35 to 40 minutes or until the rhubarb is tender. Remove the lemon slices.
Transfer to a jar or airtight container. Cover and let cool. Refrigerate until completely chilled.
You can keep the candied rhubarb for about three weeks in the refrigerator or it can be frozen. You can use it as a spread on toast, to garnish a cake or as a topping for vanilla ice cream.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.