Place pre-soaked lentils in a large pot with broth. Bring to a boil, lower heat to a simmer and cook 20 minutes. When lentils are cooked, drain them over a bowl in order to save the broth for later in the recipe.
Meanwhile, peel potatoes and cut them into chunks. In a large pot, cover them with water, add 1/2 teaspoon of salt and bring to a boil. Simmer until potatoes are cooked (you can easily poke them with a fork), about 15 minutes.
While potatoes (and/or lentils) are cooking, chop onions and fry in a large skillet, pot or wok, with 2 tablespoons of butter. After onions start to soften add minced cloves of garlic.
Add drained lentils, tomato paste, seasoned salt and stir well to combine. Add broth that was drained out of lentils and allow mixture to simmer until it thickens slightly. Pour into the bottom of a medium sized (2.5 - 3 quart) casserole dish.
Cover with peas and carrots.