With the rack in the middle position, place two 5-inch (13 cm) cast iron skillets or ramekins (1 1/4 inches/3.5 cm high) in the oven. Preheat to 400°F (200°C).
In a bowl, whisk together the oil, vinegar and mustard. Add the kale and mix well. Season with salt and pepper. Let marinate while you prepare the omelettes.
In another bowl, whisk the egg whites with the chives and mustard with an electric mixer until medium peaks form. Season with salt and pepper.
Remove the skillets from the oven. Divide the oil between the two skillets and brush to distribute. Add half of the egg white mixture to each skillet. Bake for 8 to 10 minutes or until the omelettes are puffy and golden.
Loosen the omelettes and slide onto plates. Add the cherry tomatoes to the kale and mix to combine. Garnish the omelettes with the salad. Sprinkle with the nutritional yeast.
You can find nutritional yeast in health food stores or in some supermarkets. Do not confuse it with baker’s yeast, which is light brown and granular whereas nutritional yeast is yellow and flaky.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.