In a large stockpot, bring the water to a rapid boil. Once the water is boiling, salt it liberally with generous pinch of salt.
Add the green beans and blanch* for three minutes. Directly after adding the green beans to the boiling water, get a very large bowl and fill it halfway with ice and very cold water. Get out a strainer which will be large enough to drain the beans, but small enough to sit inside the bowl of ice water.
Once the beans have cooked for three minutes, drain them and quickly plunge the strainer of drained beans into the ice bath. Make sure all of the green beans are fully submerged in the ice water. This technique called shocking, as it literally shocks the green beans with freezing temperatures. The green beans stop cooking immediately, which is what helps them to retain their vibrant color and crispness.
Drain once more and lay them out to dry on a clean kitchen towel or a few paper towels. I like to line a sheet pan with a kitchen towel and lay the beans in a single layer to pat dry with a paper towel or two.
Heat a large cast iron or stainless steel skillet over medium heat. Add the diced bacon, cook the bacon, rendering* the fat, for 3-4 minutes or until it is crisp.
While your bacon is rendering, cut your mushrooms in half (stand the mushroom on its cap and cut in half through the middle of the stem). Turn the halves cut side down, and cut into thirds. Set aside.
Once the bacon has cooked, remove it to a paper-lined plate to drain, using a slotted spoon. Leave the bacon fat in the pan.
Return the pan to the stove and heat over med-high heat. Add the onions and garlic to the bacon fat and sauté for 3 minutes or until translucent.
Add the mushrooms and sauté until they turn golden brown- about 5 minutes. Deglaze* the pan with the wine, making sure to use the spoon to scrape the bottom of the pan. Cook until the liquid has almost completely evaporated.
Add the beans and season to taste with salt, black and red peppers (if using). Take care not to oversalt as the beans were previously cooked in salted water.
Serve immediately and enjoy!