Place lentils, 3/4 cup of water and turmeric in saucepan. Bring to a boil over moderate heat, stirring occasionally. Reduce heat to low, cover and simmer for 30 minutes. Heat oil in skillet. Add mustard seeds and cook for 10 seconds. Add cumin, saute 5 seconds. Add onion and jalapenos. Saute for 5 minutes. Add cayenne and saute for 20 seconds. Add tomatoes and 1/4 cup of water. Cook for 3 minutes. Add lentils and stir. Season with salt. Reduce heat to low and simmer until mixture becomes a dry puree. Add lime juice and serve.