Remove the tri-tip from the refrigerator and let it sit at room temperature for 30 minutes.
Preheat the sous vide water bath to 131°F for medium-rare.
Mix the salt, black pepper, smoked paprika, garlic powder, onion powder, dried thyme, and dried oregano in a small bowl.
Season all sides of the tri-tip evenly with the spice mixture.
Place the seasoned tri-tip into a resealable freezer bag and remove as much air as possible using the water-displacement method, then seal the bag tightly.
Submerge the sealed bag in the preheated water bath, ensuring the meat is fully immersed, and cook for 6 hours.
When cooking is complete, remove the bag from the water bath, take the tri-tip out of the bag, and pat it dry thoroughly with paper towels.
Heat a heavy skillet over high heat and add the neutral oil. Sear the tri-tip 1 to 2 minutes per side until a brown crust forms.
Let the meat rest for 5 minutes, then slice thinly against the grain and serve with chimichurri if desired.