Whisk together tamari, hoisin, rice vinegar, sesame oil, brown sugar, garlic, and ginger. Set aside.
Optional: marinate your protein in a few spoonfuls of sauce for 15-30 minutes.
Cook ramen according to package directions. Drain and rinse with cold water. Set aside.
Turn Instant Pot to Sauté. Add neutral oil and cook onion 3-4 minutes until softened.
Add your protein: For chicken, cook 5-7 minutes stirring occasionally until mostly cooked through and lightly browned. For tofu, cook 4-6 minutes stirring gently until lightly browned (let it sit undisturbed 30-60 seconds before stirring). For shrimp, cook 2-3 minutes until just pink. For vegetable-only, skip to next step.
Stir in broccoli and baby corn. Pour in sauce and toss well.
Finish one of two ways: Sauté-only: cook 3-5 minutes until broccoli is crisp-tender. Pressure: cancel, pressure cook 1 minute on High, then quick release immediately. Turn Sauté on if needed to simmer 1-2 minutes.
Toss in cooked ramen. Stir until everything is coated.
Serve with optional toppings.