Place lentils in a large, wide pan and completely cover with hot tap water, put on medium-high heat, bring to boil then simmer for 20-40 mins, stirring every 5 mins. Check they do not boil dry, add more water if necessary.
While the lentils are cooking, prepare the rest.
Slice the red onions thinly, place into a salad bowl, sprinkle with the salt and add the vinegars and oil. Stir to combine.
Finely chop the sundried tomato and add to the onions.
De-seed & core the peppers and slice into quarters and then thin strips
Coarsely chop the parsley and add.
When the lentils are fully cooked but still retain a slight bite, drain immediately into colander and rinse with cold water, then add to the rest of the ingredients. Stir well and check for seasoning.