Meatballs in Creamy Tomato Dill Sauce

For the sauce:

• 1 tablespoon butter
• 1 tablespoon canola oil
• 1 medium onion chopped
• 2 cloves garlic minced
• 2 ribs celery chopped
• 29 ounces canned diced tomatoes with juice
• 1 tablespoon chopped fresh dill (or 1 teaspoon dried dillweed)
• ¼ teaspoon salt
• ¼ teaspoon pepper
• ¼ cup whipping cream or half-and-half

For the meatballs:

• 1 egg lightly beaten
• ½ cup soft bread crumbs
• 2 tablespoons finely chopped onion
• 1 ½ teaspoons finely shredded lemon peel
• ½ teaspoon salt
• 12 ounces ground beef or turkey
• 2 tablespoons canola oil