Soak the lentils/peas in cold water after rinsing for 1/2 to 5 hrs. In large soup pot, put in about 2 T. olive oil: add the onions, celery, carrots and leek. Sauté vegs about 10 mins or until onions are golden & vegetables are a little wilted. Add garlic and sauté about 5 minutes. Add butternut squash, dried green/brown lentils and dried split peas. Add can of tomatoes, tomato paste, 3 to 4 cups vegetable stock, Dijon mustard, soy sauce, sugar, cumin and herbs, reserving parsley for garnish. Bring to a gentle boil - then simmer on medium heat - uncovered - 20 mins. Add chopped, fresh parsley before serving. Add salt and pepper to taste. You can adjust to your taste. I like to take about 3 cups of the soup (lots of vegs) and puree or blend - and then return to the soup pot. It thickens it up nicely - even though it's messy.
TIPS: You can adjust this and use any vegetables (ie. zucchini, sweet potato) - but don't overdo the amount of vegs and try not to overcook until it's too mushy. You can also add greens that you need to use up - cabbage, spinach. You can also use frozen spinach that you've microwaved or frozen peas put straight in . You can also add 1 can butter beans (drained) into soup about 5 mins before serving. You can use this basic formula for any veg soup. Another way to thicken soup is to take about 1 cup of the veg + liquid and blend with 1 can of drained white/brown beans ie: navy and pinto. Then return to soup pot. Adjust to your taste. This soup freezes well - I put 1 cup amounts in freezer bags for quick reheating.