Rub each corn on the cob with 1/4 of the smoked paprika and salt. Put on a sheet of baking parchment on a baking tray. Drizzle with the oil and place in the oven for 25 minutes.
Meanwhile, finely chop the coriander and jalapeños. Put in a bowl with the soured cream and mix together.
When the corn in the cob have been in the oven for 25 minutes, dot each one with 1/2 teaspoon butter. Return to the oven for 5 more minutes.
Serve the corn on the cob with the dip on the side.