Press the 'SAUTE' button, and set it to 'NORMAL'. Once its displays, 'HOT', then add olive oil, let it heat up a bit, then add ground beef. Cook, crumbling the meat with a spoon until browned, about 5 minutes.
Next, add diced onions along with minced garlic, saute until the onions are translucent, about 2 minutes.
Add the seasoning mix and tomato paste. Cook for another minute.
Add 1/2 cup of broth and deglaze the pot, scraping off any browned bits stuck at the bottom of the pot. Do not skip this step, as you will get a 'BURN' error if the browned bits are left at the bottom of the pot.
Press 'CANCEL' to switch off the 'SAUTE' mode. Break the spaghetti in half and scatter it over the meat mixture in a criss-cross pattern. Pour canned crushed tomatoes all over the spaghetti. Pour in the remaining 1.5 cups of broth or water around the edges of the pot. Push the spaghetti gently under the liquid, making sure the spaghetti is covered with the liquid.
Close the lid of the Instant Pot. Set the valve to 'SEALING'. Pressure cook on high for 8 minutes. It will take some time for the pressure to build up (about 12 minutes), after which the timer will begin.
Once the cooking cycle is complete, do a quick release of the leftover pressure as per the manufacturer's instructions. Press 'CANCEL' and switch off the IP. Once the silver pin drops, turn the knob to 'VENTING' and open the lid away from you. You will find some liquid on top.
The sauce will look soupy after you open the lid (pic for reference below). Mix the spaghetti gently with the sauce. Cover and let it sit for 10 minutes on the 'KEEP WARM' mode, it will soak up all the excess liquid.
You may mix in some basil chiffonades and parmesan cheese. Dish out this easy Instant Pot spaghetti and serve topped with more basil leaves and parmesan cheese. Refrigerate leftover spaghetti in an airtight container for up to 4 days.