Sprinkle brisket all over with salt, pepper and paprika. Select Sauté setting on a programmable pressure multicooker (such as Instant Pot; times, instructions and settings may vary according to cooker brand or model). Select High temperature setting; add oil to the cooker and allow to preheat for 2 to 3 minutes. Add 1 brisket piece; cook until well browned, about 7 minutes per side. Remove from the cooker; repeat the process with the remaining brisket piece. Add onions and garlic to the cooker; cook, stirring occasionally, until starting to brown, about 4 minutes. Add broth, ketchup and tomato paste, scraping the bottom of the cooker pot to loosen browned bits. Return the brisket to the cooker. Press Cancel.