Red wine and lentil shepherd's pie with sweet potato mash

I made a variant of a BBC Good Food recipe tonight. I varied it because I had too many carrots and not enough sweet potato and on top of that, while I was cooking it, I thought, hmm, this sauce would be nicer with flour thickening it. You can also make a vegan or a gluten-free version of this recipe, or if you really want non-vegetarian for some reason, add about 150 g of chopped bacon or lardons when you add the onions. Anyway, here's my version.

Prep time: 25-30 mins, cooking time: 20 mins
Ingredients
2 tbsp olive oil
1-2 large onions, chopped (I used frozen)
10 carrots, 4 cut into sugar-cube size pieces, 6 sliced
2 tsp dried thyme (or 2 tbsp fresh thyme, chopped)
200 ml red wine
100 ml boiling water
400 g can chopped tomato
2 vegetable stock cubes (I used Kallo)
410 g can green lentils
1 heaped tbsp flour (leave out or use gluten-free substitute for gluten free)
600 g sweet potato , peeled and cut into chunks
25 g butter (vegan margarine or olive oil for vegan version)
75 g (vegetarian) mature cheddar, grated (leave out or use vegan substitute for vegan)
Salt and pepper

Method

1. Heat the oil in a frying pan, then fry the onion until golden. (For non-vegetarian version add chopped bacon or lardons at this point.) Peel and chop the first 4 carrots to sugar-cube sized pieces.
2. Add the 4 carrots and all but a sprinkling of thyme. Pour in the wine, 100ml of boiling water and the tomatoes, then sprinkle in the stock cubes and simmer for 10 mins.
3. Meanwhile, put a pan of water on to boil, peel and chop the sweet potato and peel and slice the last 6 carrots. With five minutes left on the timer (i.e. 5 mins after you started simmering the red wine mixture), put the sweet potato and 6 sliced carrots in the pan of boiling water. Open the can of lentils, but do NOT drain.
4. When the buzzer goes, reset it for a further 10 minutes, set your oven to 200C/180C fan/gas 6, then tip the can of lentils, including their juice into the frying pan. Stir in the flour and add pepper to taste. Simmer for the 10 mins left on the buzzer until the carrots still have a bit of bite and the lentils are pulpy.
5. When the buzzer goes, turn off the hob (both pans), then drain then mash the sweet potatoes and sliced carrots. Add in the butter, season to taste and stir thoroughly.
6. Pile the lentil mixture into an ovenproof dish, spoon the mash on top, then sprinkle over the cheese and remaining thyme.

7. Cook in oven for 20 mins until golden.