2 Tbs. chopped fresh parsley or basil for garnish.
Preheat oven to 450°F. Coat baking pan with olive oil cooking spray, and spray or brush potatoes with olive oil. Bake potatoes until tender, 20 to 30 minutes; allow to cool. If potatoes are large, cut in half or in thick slices before baking.
In medium bowl, pour very hot or boiling water over tomatoes and let stand until softened, about 15 minutes. With slotted spoon, remove tomatoes; reserve water.
In food processor or blender, purée tomatoes, pine nuts, garlic and basil. Gradually pour in oil and 1/4 cup reserved tomato water. Add more for a thinner pesto. Add lemon juice and season with salt and pepper.
If not already halved, cut potatoes in half (or into thick slices if large). Using a teaspoon, scoop out some potato to form a cavity for the pesto. Fill with about 1 teaspoon of pesto; place on serving plate and sprinkle with parsley or basil.