Place steak, quartered onion, pressed garlic, and broth in a 3-quart pressure cooker.
Cover cooker with lid, and seal securely. Set on high-pressure setting, if available. Cook over medium-high heat until pressure cooker steams and full pressure is achieved. Reduce heat to medium, and cook for 45 minutes.
Remove from heat; release pressure. Carefully remove lid so that steam escapes away from you. Remove meat from cooker. Let cool slightly. Strain onion mixture, reserving broth for another use; discard solids.
Sauté chopped onion and bell pepper in hot oil in a Dutch oven over medium-high heat 7 minutes or until tender. Add minced garlic, and sauté 2 minutes. Stir in remaining 1 teaspoon salt, diced tomatoes, lime juice, hot sauce, ground cumin, and pepper; cook, stirring occasionally, 7 minutes or until most of the liquid evaporates.
Shred beef, and coarsely chop; add to tomato mixture. Spoon about 1/4 cup meat mixture over bottom half of each roll; cover with tops of rolls.
*Hawaiian bread rolls may be found in the deli section of your supermarket. Other small rolls may be substituted.
Note: For testing purposes only, we used a Fagor 3-Quart MULTIRAPID Pressure Cooker. If you have another model, cook according to manufacturer's instructions.