In a large bowl, dissolve 1 tsp sugar into 1 cup warm water then sprinkle in yeast. Let sit until frothy, 5-10 minutes. Stir in flax egg, vanilla, lemon juice, remaining sugar, and oil.
To the bowl, add 3 cups of flour and salt (there's no need to mix dry ingredients separately) and stir until a shaggy dough forms. Turn out onto a floured surface and knead until smooth and elastic, adding up to 1/2 cup more flour if necessary, about 5 minutes. Grease a bowl, add the dough, then turn to lightly coat in oil. Cover with plastic wrap and set aside to rise until doubled, about an hour.
Using about 1/2 tbsp of the melted coconut oil, grease a loaf pan. Flour your work surface and a rolling pin generously.
Roll out dough until you have a rectangle about 12 inches by 20 inches, (you don't need to be precise). Using a pastry brush, brush the dough with 1 - 1 1/2 tbsp melted coconut oil so it is lightly covered. Sprinkle the surface evenly with chopped chocolate and halva, pressing into the dough lightly to hold it in place.
Cut the dough into six vertical strips. Lifting carefully, layer the strips so you have three two-layer strips of dough (some of the filling may fall out, that's okay). Cut each double strip horizontally into five squares. Assemble the bread by placing all the squares into the loaf pan vertically. Once all your squares are in the pan, sprinkle any of the chocolate and halva that fell out during the layering process on top. Brush with remaining coconut oil, then cover lightly with plastic wrap and set aside to rise for another hour.
Bake at 350F for approximately 30 minutes, until the tops are golden and bursting from the pan and the bottom sounds hollow when tapped.