Cut the baguette into 18 x 1 ½cm thick slices. Spoon the flour in a sieve. Whisk eggs and 3 tablespoons cold water together in a shallow dish. Combine the panko crumbs and Parmesan in a shallow dish.
Lightly dust both sides of the baguette slices with flour. Then one at a time dip into the egg then breadcrumbs, using fingertips to press crumbs on. Combine the goats cheese, sour cream, chives and basil, season.
Cover the base of a non-stick frying pan with oil and heat over medium heat until hot. Cook the crumbed bread in batches, for 2 minutes each side or until golden. Transfer to a wire rack to cool. Spread the goats cheese over one side of each bread slice. Top with quince paste or onions.
Drape gold leaf carefully over each tomato then place on the baguette. Garnish with small basil leaves. Serve immediately.