Put the shrimps in a large bowl of cold water and let them thaw for about 15 minutes, changing water after 5-10 minutes if necessary. Defrost peas in a bowl at room temperature. Peel and finely chop the onion. Prepare pasta in boiling salted water according to package instructions
Remove the shrimps from the water and dab dry. Heat the oil in a large coated pan. Fry the shrimps for 1-2 minutes. Add diced onion and peas and fry for about 1 minute more. Add sauce and milk and simmer for 1-2 minutes. Season the sauce with salt and pepper if necessary
Drain the pasta and add to the sauce. Mix sauce and noodles, arrange on plates and garnish with dill if desired