Place saucepan over medium-high heat and bring to a boil without stirring. Let bubble briskly for 4 to 5 minutes or until the sugar begins to change color. Without stirring, swirl pan gently on the unit until the color becomes deeply golden. Avert your face (as hot steam rises) and near the side rather than in the middle of the pan, pour in brown sugar mixture. Boil briskly for 5 minutes. Slide pan off heat and stir in butter, lemon juice and vanilla. The syrup is extremely hot so leave to cool in pan on stove until warm. Syrup thickens as it cools. (Once cooled, cover and refrigerate if making ahead. Warm briefly in microwave; stir well before serving.)

To make waffles, mix flours with poppy seeds, baking powder, baking soda and salt in a large bowl. Peel very ripe banana; use a fork to mash, leaving some texture. Stir milk with banana.

Using an electric mixer or whisk, beat egg whites until soft peaks form. Whisk milk mixture and melted butter into flour mixture until almost smooth; some small lumps remain. Fold in egg whites.

Preheat waffle iron until very hot. Spray grids with nonstick spray if needed. Bake in batches for 4 to 5 minutes or until waffles are golden and crisp. Keep waffles warm directly on oven rack while making more. (If making ahead, cool waffles on a rack; cover and keep at room temperature for up to a day or freeze. Lightly toast waffles in toaster oven to restore crispness.)

Meanwhile thinly slice bananas. Pile on top of waffles and sprinkle with fresh berries. Serve waffles with a pitcher of warm syrup.