With the rack in the middle position, preheat the oven to 200 °C (400 °F).
Butter eight 125 ml (½ cup) ramekins.
In a saucepan, melt butter. Add flour and cook over low heat for 1 minute, stirring constantly. Add bell pepper purée and milk while whisking. Bring to a boil, stirring constantly.
Off the heat, add cheese and egg yolks while whisking. Let cool.
In a bowl, beat egg whites with cream of tartar and salt until stiff peaks form. Season with pepper. With a spatula, gently fold half the egg whites into the bell pepper sauce. Fold in remaining egg white mixture.
Spoon into ramekins and place on a baking sheet.
Bake for 15 to 18 minutes or until soufflés are puffed and golden brown. Serve immediately as an appetizer.
To obtain 180 ml (¾ cup) of red bell pepper purée, you will need two roasted red bell peppers, skin and seeds removed. Purée in a food processor until smooth. You could also use store-bought jarred roasted bell peppers to make purée.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.