1. In a skillet, heat oil over medium-high heat for 30 seconds. Add bacon and cook until crisp. Drain on a paper towel and crumble. Cover and refrigerate until ready to use. Drain off all but 2 tbsp (25 ml) fat from pan.
2. Reduce heat to medium. Add onions, celery and carrots to pan and cook, stirring, until softened, about 7 minutes. Add garlic, thyme and peppercorns; cook, stirring, for 1 minute. Add wine, bring to a boil and cook until reduced by half, about 3 minutes. (If you are using water, add it with the tomatoes.) Add tomatoes with juice, clam juice and water; bring to a boil. Transfer to slow cooker stoneware.
3. Stir in potatoes. Cover and cook on Low for 8 hours or on High for 4 hours, until potatoes are tender.
4. Discard any clams that are open. In a large saucepan, over medium-high heat, bring ½ cup (125 ml) water to a rapid boil. Add clams, cover and cook, shaking the pot, until all the clams open. Discard any that do not open. Strain cooking liquid through a fine sieve. Using a fork, remove clam meat from shells.
5. Add clam meat and cooking liquid to slow cooker, along with corn and reserved bacon. Cover and cook on High for 15 minutes, until corn is tender and mixture is heated through.
6. Ladle into bowls and garnish liberally with parsley.
Complete Steps 1 and 2. Cover and refrigerate for up to 2 days. When ready to cook, continue with the recipe.