01 - Place the peeled and diced potatoes in a large pot, cover with salted water, and bring to a boil over high heat. Reduce to a simmer and cook for approximately 15 minutes until the potatoes are fork-tender.
02 - While the potatoes cook, heat a small skillet over medium heat. Add the diced red bell pepper, jalapeño, and minced garlic. Sauté for 3 to 4 minutes until softened and fragrant, then remove from heat.
03 - Drain the cooked potatoes thoroughly in a colander and return them to the pot. Mash with a potato masher until smooth and free of large lumps.
04 - Pour in the milk, add the sour cream and shredded cheddar cheese, then stir until the mixture is creamy and the cheese begins to melt into the potatoes.
05 - Gently fold in the sautéed pepper and jalapeño mixture, sliced green onions, ground cumin, smoked paprika, chili powder, and season with salt and pepper to taste.
06 - Taste the mashed potatoes and adjust the salt, pepper, or spices as needed to achieve the desired flavor balance.
07 - Transfer the finished mashed potatoes to a serving bowl, garnish with fresh chopped cilantro if desired, and serve immediately while hot.