Fill a large pot with water, salt and potatoes and bring to boil. Cook until fork tender.
Meanwhile, heat oil in a medium sauce pot over medium heat. When oil is hot add onions and peppers and saute for 3 minutes. Add the garlic and cook until it begins to brown. Lower the heat and add tomato paste and stir for 3 to 5 minutes. Deglaze with white wine and reduce by half.
Add tomato sauce and bring to simmer for 5 minutes. Then stir in butter and cream and set aside, covered to keep warm.
When potatoes are fork tender, drain water and mash slowly adding the sofrito mixture. Season with salt and pepper and garnish with cilantro.