>>"what exactly do the color codes of lenils mean?"
the color is not code, just the color of the bean. texturally they cook up differently. they don't taste the same.
french de puy (green) lentils make the best soups--velvety without losing their shapes. (and not looking drab brown.)
we have a very simple family recipe for Bengali Dhal with lemons which is worth trying
You can use any number of variations of spices, but try this one for starters
1 & 1/2 cups washed red lentils
1 white onion chopped
2 cloves garlic peeled
1in fresh ginger peeled
2 red chillies chopped and de-seeded
2 small unwaxed lemons quartered
1 large whole chilli pricked with a fork
3-4 cups water ( more if needed - this is a watery soup)
1 tsp Panch Phoron ( Bengali mix of whole fennel seeds, mustard seeds, cumin seeds, nigella seeds, fenugreek seed ) OPTIONAL
1 tsp ground ginger
1 tsp ground turmeric
1 tsp ground mustard ( coleman's is fine )
3 tblspn vegetable oil or ghee
Place the ginger and garlic in a blender with a little salt and water and blend to a paste.
Heat the oil/ghee in a pan and add the panch phoron. Saute for a minute or so until the seeds begin to pop.
Add the chilli and saute gently until they release their flavour
Add the onions and saute until it begins to colour
Add the dry spices and cook for two mins or so until they lose their rawness. If it begins to stick, add a tsp or so of water
Add the lentils and stir well in the spice mixture.
Add the water and stir well.
Add the lemons
Add the whole chilli ( pricking with a fork allows it to release flavour without too much heat )
Cook gently for c45 mins ( it can be prepared more quickly, but the longer you cook, the better - you can leave it in a slow cooker all day and,like many things, it is better served reheated the next day)
Add more water if needed to keep a soupy consistency.
Serve the lemony water in glasses first and then serve the dhal with plain boiled rice or a paratha.
Hope this helps
Never seen red lentils used in soup; however, have eaten red lentil dal (an East Indian dish) made by a good friend's grandmother. It's really wonderful if you like Indian spicing.
Searched for an online recipe by Madhur Jaffrey, and came upon the one linked below. Never had the sweet and sour version, but Jaffrey is a good source if you can find her cookbooks. I'd serve w/ an Indian bread (naan or chapati), curried cauliflower or green beans, raita (a yogurt condiment) for cooling properties. You won't miss the meat...