In a large pot, heat oil.
Add onion and sofrito.
Saute until onions are softened.
Add potatoes, cumin and oregano.
Toss well to coat the potatoes with the spices.
Add milk and 1 cup water. Bring to a boil. Reduce to a simmer.
Cook with pot partially covered for 10 minutes.
Add salt and raise heat to medium high.
Add pasta and cook for 3-4 minutes. (If using larger, shaped pasta, it will take longer to cook until al dente.)
Add cheese and another cup of water. Simmer for 5 minutes.
Add cilantro and stir to combine.
Adjust salt, as needed.
Serve warm, garnished with a little of the achiote oil.