In a medium saucepan, bring 2 cups of the water to a boil. Add the lentils, cover and cook over low heat, stirring occasionally, until almost tender, about 30 minutes. Add a large pinch of salt and simmer until tender, about 3 minutes longer. Drain the lentils and spread them on a plate to cool.
Heat the olive oil in a medium, enameled cast-iron casserole. Add the onion and shallot and cook over low heat, stirring, until softened, about 5 minutes. Add 2 cups of the water, 1/4 cup of the parsley, the thyme, bay leaf and a pinch of salt and bring to a boil. Cover and simmer over moderately low heat for 15 minutes. Add the peas, rice and the remaining 1 quart of water. Cover and cook over moderately low heat, stirring occasionally, until the rice is tender, about 20 minutes.
Meanwhile, in a small bowl, toss the olives with the garlic, lemon zest and the remaining 1/2 cup of parsley. Season the gremolata with salt.
Gently stir the lentils into the stew. Add the romaine and crushed red pepper, cover and cook over low heat until the lettuce is wilted, about 3 minutes. Season with salt. Discard the thyme sprigs and bay leaf. Ladle the stew into bowls, top with the olive gremolata and serve.
Wine Recommendation: The salty olives and earthy lentils in this stew call for a big white (try the 1999 Regaleali Bianco from Sicily) or a light red with good acidity (such as the 2000 Antinori Santa Cristina).