Using a peeler or mandolin slicer, slice the cucumber, radishes and watermelon radishes into very thin circular slices, set aside.
Note: if slicing in advance, place the slices in cold water and set in your fridge for up to a day—the watermelon radishes will give off an odor the longer they set out so you may opt to not slice the watermelon radishes in advance.
Toast your bread, dry, in the oven at 350F until toasted but not browned.
Allow your toast to cool for 5 minutes.
Generously spread the cheese mixture from the Southern Cheeseball recipe onto the toasted sourdough.
Layer your sliced vegetables—I love to overlap the slices because once it is cut they look so colorful and artistic.
Grate fresh lemon zest over the top and garnish with black sesame seeds.
Season with salt & pepper—cut the toasts on a bias or into 4 little triangles and place on a serving platter.