Mix together all the spice blend ingredients (2 tsp garam masala, 1 ½ tsp ground cumin, 1 ½ tsp ground coriander, 1 tsp ground turmeric, ½ tsp cayenne pepper adjust, and 1 tsp kosher salt plus more) in a small Mixing Bowl. Set aside.

Heat the 2 tbsp neutral oil such as vegetable or canola oil in a large Skillet over medium-high heat. Add the diced 1 yellow onion finely diced and cook, stirring occasionally, until softened and lightly golden — about 5 to 6 minutes.

Add the 4 cloves garlic minced and 1 tbsp fresh ginger grated or finely minced to the Skillet. Stir constantly and cook for 1 to 2 minutes until fragrant.

Add the spice blend to the Skillet and stir it into the 1 yellow onion finely diced mixture. Cook for 1 minute, stirring constantly.

Add the 1 ½ lb boneless skinless chicken thighs cut into 1-inch pieces pieces in a single layer. Stir to coat them in the spiced 1 yellow onion finely diced mixture. Cook for 3 to 4 minutes, stirring occasionally, until the 1 ½ lb boneless skinless chicken thighs cut into 1-inch pieces is lightly browned on the outside (it doesn't need to be fully cooked through yet).

Pour in the diced 1 can diced tomatoes (with their juices) and stir well, scraping up any browned bits from the bottom of the Skillet. Let the mixture cook for 3 minutes, allowing the 1 can diced tomatoes to break down slightly.

Pour in the 1 can coconut milk full-fat for best results and stir everything together. Add the optional teaspoon of 1 tsp sugar if your 1 can diced tomatoes taste acidic. Bring to a gentle simmer — do not boil hard or the 1 can coconut milk full-fat for best results can separate.

Rinse peppers under cold water and pat dry. Slice off tops and bottoms, stand upright, and cut down along the inside to remove seeds and white ribs. Slice lengthwise into ½-inch strips; halve crosswise for shorter pieces. Keep sizes uniform so everything cooks evenly. If adding onion, slice it now. Measure out olive oil, salt, and pepper. Have everything ready before the pan goes on — sautéing moves fast.

Heat a large Skillet over medium heat. Add 1 tbsp olive oil per 2 peppers; warm 30–60 seconds until shimmering. Add pepper strips in a single layer — work in batches if crowded. Season with salt and pepper, stir to coat. Cook over medium heat, stirring every 2–3 minutes, for 6–10 minutes. At 6 minutes: slightly softened with snap. At 10 minutes: tender throughout with light color. For very soft peppers, cook 30–40 minutes over medium-low, stirring occasionally. Add garlic halfway through cooking. If browning too fast, add a splash of white wine or water and briefly cover to steam.