Divide rice, reserving 3 Tbsp for the next step. Cook remaining rice according to package directions. In a bowl whisk together 1.5 cups warm water, peanut butter, and tamari, set aside.
Add the reserved jasmine rice to a large pot over high heat. Toast the rice, stirring constantly, until it browns slightly and smells nutty, about 5 to 8 minutes. Transfer the toasted rice to a food processor and pulse into a coarse powder.
Return the pot to medium-high heat with 2 tbsp vegetable oil. Once hot, add sliced onion, minced garlic, and cubed eggplant.
Cook, stirring occasionally, until the eggplant softens and browned, approximately 7 minutes. Stir in tomato paste and season with 1/4 tsp salt and 1/2 tsp pepper. Cook until the tomato paste is fragrant, approximately 1 minute.
Add the toasted rice, tamari, peanut butter, and water mixture and chopped baby bok choy to the pot.
Stir well to combine and bring to a boil. Cover, reduce to heat to medium-low and simmer stew until thickened, approximately 6 to 7 minutes.
Serve stew over jasmine rice topped with chopped peanuts and scallions.