Combine 3 cups cold water, lentils, and salt in a medium saucepan; bring to boil. Reduce heat, cover, and simmer until lentils are tender, 20 to 25 minutes.
Drain, reserving 1 cup of the cooking liquid; set lentils and reserved liquid aside.
Heat oil in heavy large skillet over medium-high heat. Add onion, and cook until browned, about 20 minutes. Add carrot, rosemary, and thyme, and sauté 4 minutes. Add garlic, and sauté 30 seconds. Reduce heat to medium-low. Mix flour into vegetables; cook 1 minute. Add vegetable broth and reserved lentil cooking liquid.
Mix in potatoes, soy sauce, and tomato paste. Cover; simmer until potatoes are tender, stirring occasionally, 13 to 15 minutes. Add lentils; season with salt and pepper. Divide filling among four 2-cup ovenproof bowls.
Filling can be made 2 days ahead. Cover; chill. Bring to room temperature before continuing.
To make TOPPING:
Preheat oven to 400° F. In a large bowl, mix together flour, cornmeal, baking powder, and salt. Add butter and rosemary, and blend with a pastry blender or fork until mixture resembles coarse meal. Add buttermilk, and mix with clean hands until dough forms moist clumps. Turn dough out onto lightly floured surface. Divide into 4 equal pieces; shape each into 2/3-inch-thick disk. Set rounds atop filling.
Bake pies on baking sheet until tester inserted into biscuit topping comes out clean, about 30 minutes.
*Cook's Notes: If you don't have or don't want to buy fresh buttermilk, get some powdered buttermilk and keep it in an airtight container in your cupboard. It pretty much lasts forever. And, you can use it in almost anything instead of fresh buttermilk. I don't use it for things like buttermilk pancakes where the buttermilk is the main ingredient. But, for biscuits on top of a pot pie, it works like a charm. And, you can reconstitute it in water or milk, your choice. I used milk for these biscuits because I wanted the extra body that milk has.
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