Make sure your starter is well-fed, bubbling, and ready to rock.
Put the flour and salt into the bowl of a stand mixer. Stir to combine. Add the egg, milk, oil, and yeast mixture. Knead to make a smooth, very soft dough. The dough should stick a bit to the bottom of the bowl.
Place the dough in a lightly greased bowl, cover, and let it rise until it is doubled in size, about 45 to 60 minutes.
Meanwhile, thoroughly drain the tomatoes, patting them dry. Use kitchen shears to cut them into smaller bits. You can use scissors to cut the basil and oregano leaves. Break the feta up and shred the cheddar.
Gently deflate the dough. Flatten and pat it into a 22" x 8 1/2" rectangle.
Spread with cheese, tomatoes, and herbs.
Starting with one long edge, roll the dough into a log the long way. Pinch the edges to seal. Place the log seam-side down on a piece of parchment paper at least as long as your pizza stone.
Using kitchen shears, start 1/2" from one end and cut the log lengthwise down the center about 1" deep, to within 1/2" of the other end.
Keeping the cut side up, form an "S" shape. Tuck both ends under the center of the "S" to form a "figure 8;" pinch the ends together to seal.
Cover and let rise in a warm place until double, 45 to 60 minutes.
While the loaf is rising, put your pizza stone in and preheat the oven to 350°F / 176°C.
Uncover the bread. Sprinkle the sesame seeds over it. Use either a pizza peel or an upside-down cookie sheet to slide the bread and parchment paper onto the pizza stone. Bake it for 35 to 40 minutes, tenting it with foil after 20 to 25 minutes to prevent over-browning.
Remove the bread from the oven, and transfer it to a rack to cool. Enjoy warm or at room temperature. Store, well-wrapped, at room temperature for a couple of days; freeze for longer storage.
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