There are a million version, here is one we like.
600g each potatoes and sweet potatoes; peeled & in 2cm chunks
1 onion, 2 carrots, 3 cloves garlic, 2 sticks celery; finely sliced
1 tablespoon coriander seeds, ground fine
½ a small bunch of thyme, leaves only
~12 sun-dried toms (rehydrated), chopped
2 tablespoons balsamic vinegar
splash of red wine
100ml veg stock
1 tin each lentils and chickpeas (with juice)
5 sprigs of parsley
2 sprigs rosemary (leaves)
1 lemon (zest only)
Salt and pepper
Heat potatoes in large pot of cold salted water to boil. Simmer 5 mins, add sweet potatoes and simmer to tender (5-10min more). Drain, let dry, and return to pan with oil, salt & pepper. Mash and set aside.
Saute onions, garlic (reserve 1 clove for topping), carrots, celery & coriander in a good glug of oil. Add thyme and cook 10min to soft. Add mushrooms, sundried tomatoes and vinegar. Cook 10mins, add wine and turn heat up to bubbling. Stir in stock, lentil, chickpeas and cook a further 5- 10min to thicken and reduce. Stir in parsley, season.
Pour into large baking dish (~25cm x 30cm) and top with mash.
Combine garlic, rosemary, lemon zest, breadcrumbs and 1tbsp olive oil. Mix well and sprinkle over mash. Bake 10min. Grill 2-3min to golden.