In a pot of boiling salted water, cook your peas and set aside.
Peel and chop the onions. Fry them in butter and olive oil until they blanch and melt.
Add the peeled and diced tomatoes.
Season to taste with salt and freshly ground pepper, then add the basil.
Simmer over low heat for about 15 minutes.
Add the peas and simmer again for about 10 minutes.
Pour the soup into a bowl, decorate with a few sprigs of parsley.
Serve with crispy Sigdal Herbs and Sea Salt.