Chop the onion finely and mince the garlic. Slice the bell peppers into thick strips. Prepare all ingredients nearby for easy assembly.
In a skillet over medium heat, add olive oil and sear the chicken thighs until golden on all sides, about 3-4 minutes per batch. This step adds depth of flavor and a lovely aroma.
Transfer the seared chicken to the slow cooker. Add the chopped onions, minced garlic, sliced bell peppers, and canned tomatoes with their juices. Stir in smoked paprika and season with salt and pepper.
Pour the chicken broth over the ingredients in the slow cooker. Cover with the lid and set to low for 6 to 8 hours, or high for 3 to 4 hours. The house will fill with a smoky, savory aroma as it cooks.
About 30 minutes before serving, taste the sauce and adjust seasoning if needed. If the sauce is too thin, mash some of the tomatoes with a spoon to help thicken it.
Once the chicken is tender and falling apart, turn off the slow cooker. If desired, stir in a dollop of sour cream or Greek yogurt for creaminess and a tangy finish. Let it sit for a few minutes to meld flavors.
Serve the goulash hot, spooned into bowls, with crusty bread or over noodles. Garnish with fresh herbs if you like, and enjoy the warm, smoky flavors that fill the house.