In a medium sauce pan, bring the vegetable broth to a simmer. Add the porcini mushrooms, tomato paste, and fennel. Let mixture simmer until it is reduced to about half the size and the porcini mushrooms are tender, about 45 minutes. At this point you can save the mixture until ready to serve, or finish the recipe. To finish the recipe, add the riced cauliflower to the mushroom mixture and stir in. Add the peas and stir in. Cover and let simmer for about 10 more minutes. Stir in optional nutritional yeast and taste for salt and pepper. Serve immediately topped with the fresh herb tops of the fennel. NOTE: With the cauliflower, you can have more of a brothy finished dish (as pictured) by just adding 2 cups, or add 3 cups to soak up more of the mushroom broth. Porcini mushrooms have a very rich, robust flavor, so you may find that more cauliflower helps mitigate the rich flavor of the porcini mushrooms. Or, if you are like me, you will welcome the hearty flavor of the mushrooms and actually want to drink the extra broth like a rich consommé.