Spray the Instant Pot with low-calorie cooking spray and set to ‘sauté.’
Add the onions and cook for 5-10 minutes until soft and golden, stirring well. Add the garlic and continue to cook for 1-2 minutes.
Add the peppers and cook for 5 minutes. Then add the minced beef and cook for a further 4-5 minutes, until browned.
Add the chilli powder, smoky BBQ seasoning, paprika, and cumin. Stir in and cook for 1-2 minutes.
Add the chopped tomatoes, tomato puree, kidney beans, balsamic vinegar, Worcestershire sauce (or Henderson's relish), sriracha, and beef stock. Stir well, then cover with the lid and lock. Set the valve to 'sealing', and cook at high pressure for 30 minutes. Release the pressure, and when the valve has dropped, remove the lid.
The chilli should be thick and rich; if it's still a little runny, set to 'sauté' and continue to cook with the lid off until reduced and thickened. Then serve!