Set your Instant Pot to SAUTE. Saute the diced onion and pepper in the butter for 3-5 minutes, or until tender.
Stir in the garlic, ginger, garam masala, turmeric, paprika, cumin, cayenne, salt, and black pepper. Cook and stir for another minute, or until fragrant.
Add the chicken bouillon, diced tomatoes, tomato sauce, and sugar. Stir to remove the cooked bits from the bottom of the pot. Add the diced chicken.
Seal the Instant Pot and set it to MANUAL high pressure for 10 minutes. (It will take 10-12 minutes to come to pressure.) When it beeps, use quick release, then carefully remove the lid.
Whisk together the cream and flour until smooth. Switch back to the sauté setting, then stir in the cream mixture. Cook and stir for about 3 minutes, or until sauce is thickened.
Serve hot over basmati rice.