Roast the peppers over a gas flame or broiler until the skin has blackened. Place them in a bowl, cover to steam, then peel, seed, and cut into strips.
In a large pot, heat the olive oil over medium heat and sauté the onions until translucent. Add the diced potatoes and chicken broth, then bring to a simmer.
Cook the potatoes in the simmering broth until tender, about 20 minutes.
Add the peeled and diced Roma tomatoes, roasted pepper strips, and milk to the pot. Let it simmer for a few more minutes.