Take Bone-in Pork Shoulder (1) out of the fridge and allow to come to temp. Make sure to pat it dry. If there is excessive fat, make sure to remove it.
While the pork shoulder comes to temp, julienne the Yellow Onion (1), cube the Carrot (2), thinly slice the Celery (1 stalk), Garlic (2 clove) and Serrano Chili (2).
Heat the Olive Oil (1 tablespoon) in your pressure cooker over medium-high heat. Season the pork heavily on all sides with Salt and Pepper (to taste). When the oil begins to smoke, sear on all sides until a nice golden brown.
Remove the seared pork and set aside. Add in the onions, carrots, celery and pepper, Fresh Thyme (1 sprig) and Fresh Sage (1 sprig), and saute for 5 minutes over medium high heat. Season with a bit of salt and Serrano peppers.
Add in the garlic and saute until fragrant.
Once fragrant, add the Canned Whole Peeled Tomatoes (28 ounce) and Chicken Stock (29 fluid ounce). Crush the tomatoes using a pair of tongs. Season again with a bit more salt and pepper.
Add the pork back to the pan and set it right in the middle of all that goodness. Then apply the lid to your pressure cooker and heat over high heat, while you wait for the pressure to seal the lid.
Once the seal has been made, turn the heat to medium-low, so you can hear a slight whistle from the top. Cook for one hour.
After the hour has past, either run the pressure cooker under cold water to release the seal or pop a spoon under the whistle to release the pressure.
Remove the pork shoulder from the tomato sauce and cover in a large bowl or plate with aluminum foil. At this time, remove the sprigs of thyme and sage from the tomato sauce.
Bring a pot of water to a boil, and prepare the Spaghetti (200 gram) according to package's instructions.
Now, prepare the tomato gravy. Begin by melting the Butter (2 tablespoon) in a large pan over medium-high heat.
Once melted, add the All-Purpose Flour (2 tablespoon).
Cook while stirring for 3 minutes, until the roux is a nice blonde color.
Add in tomato sauce and stir to combine over medium heat.
Cook for 5 minutes until thickened. If too thick, add a bit of Water (to taste).
Shred the pork shoulder with forks or a pair of clean hands.
Add the shredded pork to the tomato gravy, along with the cooked pasta. Stir to combine. Give everything a taste, and season with salt, pepper and Sriracha (to taste) for more heat.
Plate and serve. Feel free to add your garnish of choice.