Help Identifying Finnish Meal

Hi everyone :) I’m from Ontario, Canada and recently visited my first Finnish spa. Had the most incredible lunch of this delicious sausage on a bun. No phones are allowed in the spa and they do not post their menu online so I have no idea what it was (also emailed spa and they didn’t want to share recipe). Remember it saying it was an apple and sage sausage, definitely tasted like pork and was dressed with pickled beats and the most delicious white condiment (kinda mayo-ey, kinda sweet, garlic). It was honestly one of the best sausages I’ve ever had and would love some help identifying so I can replicate at home. Any guidance would be greatly appreciated!