Fry the onion until soft. Add all the other ingredients EXCEPT the thyme, oregano, and parsley.
Bring to the boil, lower the heat and simmer, covered, until the lentils are tender, about 45 minutes.
Check and stir occasionally, as you want to monitor the water levels. If it's drying out, add some water; if it seems too liquid after 30 minutes or so, take off the lid to let the moisture evaporate.
Add the thyme and oregano before serving, when the stew has thickened and the lentil are soft.
Check your salt levels and season accordingly at this pont, and to serve, garnish with the parsley.