Make the bread: Stir together the flour and salt.
Fill ½ cup with tepid water. The water should feel neither hot nor cold when you put your finger in it. Drop in ¼ teaspoon active dry yeast and let it dissolve for 5 minutes.
Stir the water and yeast into the flour mixture. You might need to add a little more water, a tablespoon at a time, until you get a nice pliable dough (you're aiming for a dough that feels somewhat like your earlobe)
Cover the bowl with the dough with plastic wrap and let it sit out at room temperature for about 8 hours, or up to 24 hours. (Make the dough in the morning before you go out for the day.)
Preheat the oven to 420 °F
Put a sheet of parchment paper on a baking sheet.
Divide the dough into fourths on a lightly floured surface (sprinkle everything with flour to avoid sticking) Use a rolling pin to roll each ¼ of the dough into a circle, about ¼-inch thick.
Sprinkle 1 ounce of cheese onto each piece of dough.
Lay 2 slices of ham on top of each piece of dough.
Put the gherkin pickles right in the middle and roll the whole thing up like a cinnamon roll, or something like that.
Lay each sandwich roll on the parchment-lined baking sheet. Bake for about 20 minutes.