Potatoes can be good cold if you think of them in the potato salad category. I sometimes make potatoes with on plan mustard and egg whites.
For combined carb/protein the granola recipes (under Breakfast in the recipe forum) are great as are some muffins (coconut muffins, breakfast bars for example).
Baked sweet potato chunks are great cold. I cut mine into ~1" slices and bake about 50 minutes.
Radishes and jicama are also considered carbs (see the additions to the infinite menu planner in the FAQ section) and they are great cold.