For the crepes:
Sift the flours together with the salt into a bowl. Make a well in the center, and crack the eggs into it, then pour in the buttermilk, and oil. Whisk the liquids together, then gradually draw the flour in from the sides to make a smooth batter. (If necessary, add water.) Cover the bowl with plastic wrap, and let sit at room temperature for 2 hours. Before frying, stir in enough water to bring the batter to the consistency of thin cream.
Heat a crepe pan and brush lightly with clarified butter. Pour in a spoonful of batter and swirl it around the crepe pan to coat the bottom and make a thin sheet. Fry the batter until the edges crispen and curl slightly, and the underside is golden, about 3 minutes. Flip and continue cooking to finish, about another 2 minutes. Continue making the crepes, piling them up and keeping them warm as you continue.
For the tomatoes:
Melt the butter in a saute pan. Add the tomatoes, cut-side down. Poke their backsides a few times with the tip of a knife to prevent the skins from bursting. Cook 10 minutes. Flip, and cook 5 minutes on the other side, scattering over the thyme as you do so. Season the tomatoes with salt, and pepper, to taste. Pour over the cream, and cook until reduced to a thick sauce around the tomatoes, about 5 minutes depending on your heat. Serve.
For the plate:
Fold a crepe and place it on a plate, then top it with tomatoes and sauce. Enjoy!