Preheat the oven to 175°C/347°F.
Add the cut vegetables into baking pan, drizzle with coconut oil, season with salt and pepper, toss to coat evenly and roast for 30 minutes.
While the vegetables are roasting, add the lentils and bay leaf into a sauce pan with water, bring to boil over medium heat, then turn the heat to low and simmer for 15 minutes, until cooked. Set aside. (use one part lentils and one&a half parts water, to ensure the lentils absorb all the liquid, and you won't loose the minerals leaked into the cooking water).
Prepare the dressing - add the mustard, olive oil, horseradish and vegetable broth into the blender and process to obtain a creamy liquid. Add the lemon juice and pulse to incorporate. Set aside.
Remove the roasted veggies from the oven, add the lentils and chopped parsley and toss to combine.
Serve with warm horseradish sauce.