Prepare your bordelaise sauce before you start cooking your steak as it will take some time to reduce.
Prepare demi glace according to product container. See notes below.
Note: Use a large sauté pan that is deep so you can cook your sauce in the same pan.
In large sauté pan, on medium high heat, cook wagyu bacon slices until fully cooked. Set wagyu bacon aside
Set wagyu bacon aside (on plate covered with a paper towel). Leave ¼ of the bacon fat in the pan and spoon ¾ of the bacon fat into a small bowl (set aside in refrigerator). You want your bacon fat to return to a solid state in the refrigerator.
Add shallot and carrot to wagyu bacon fat and cook until carrots start to soften. During the cooking process, if needed, you can add additional olive oil if you run out of wagyu bacon fat (amount can vary).
Add garlic, thyme and bay leaf. Cook for 1-2 minutes until fragrant but do not overcook garlic.
Add Bordeaux or dry red wine. Cook until liquid is reduced by half.
Using a fine mesh sieve, strain sauce to remove carrot, shallot, thyme and bay leaf. Add liquid back to pan.
Add demi glace and reduce until thickened.
Remove from heat and quickly whisk in remaining wagyu beef bacon fat. Season with salt to your taste.