Pour the wine and water into a 4-quart saucepan , and drop in the garlic, onion, carrot, celery, porcini, rosemary, and 1/2 teaspoon salt.
Bring to a boil, set the cover ajar, adjust the heat to maintain a steady simmer, and cook for an hour or more, until the vegetables have exhausted all their flavors and the liquid level has reduced by half.
Set a sieve over a bowl, and pour the entire contents of the saucepan into it, straining out the solids and collecting the sauce in the bowl.
Press the vegetables with a big spoon to release more sauce.
Rinse the saucepan, pour the strained sauce back into it, and bring to a boil.
Cook, uncovered, adjusting the heat so the sauce reduces steadily without scorching, until thickened and flavorful, about 1 1/2 cups in volume.
Season with 1/2 teaspoon salt, and keep the sauce warm.
Meanwhile, tie loops of kitchen twine tightly round the filet to keep it compact, even in shape, and easier to handle.
Tie the first loops an inch in from either end of the filet, and more loops at 2-inch intervals along the length.
When you are ready to cook the filet, sprinkle the remaining teaspoon salt all over its surface.
Pour the olive oil into a 12-inch saute pan or skillet; set it over med-high heat, and put in the beef.
Pan-sear the filet for 15 minutes, more or less, depending on how well-done or rare you like it.
Frequently roll and shift the tied meat in the pan, so it cooks and colors evenly on all sides, until crusty on the outside and med-rare inside.
Turn off the heat and put filet on a warm plate.
To finish the sauce, pour it all into the searing skillet, turn on the heat, and bring the liquid to a boil while scraping up all the browned bits from the skillet bottom.
Stir to incorporate this flavorful glaze into the sauce as it heats.
While the sauce is boiling, drop in the cold butter, one piece at a time, vigorously whisking each one to incorporate it fully with the sauce before adding the next piece.
When the last bit of butter has disappeared in the sauce, turn off the heat and stir in the honey until it disappears.
To serve: slice the meat crosswise into 1/2-inch slices, snipping and removing the twine loops as you cut.
Drizzle some of the wine sauce on a warm rimmed serving platter, and arrange the beef slices on top of the sauce (or drizzle a couple spoonfuls of sauce on rimmed dinner plates and top with individual portions of sliced beef).
Serve immediately, with remaining sauce in a bowl to be passed at the table.