How about fruit and cheese, @Scienceisnotopinion? Or a mixture of celery, cherry tomatoes, cheese and cold meat.
You could do oven roast veg for dinner, and mix the left over roasted veg with cous cous to make a salad, with feta or goats cheese.
Roast tomatoes, garlic and red peppers, and mix through cooked pasta - not necessarily something you can cook in advance, but it would be quick and easy to cook. Same goes for fried rice - cook extra rice the day before, then make fried rice with spring onions and add left over chicken or pork, or cooked prawns.
We cook a baked rice dish which is good the next day, microwaved/reheated.
Cube chorizo and chicken (I use boneless thighs, but it works as well with breast), and fry in a bit of olive oil. Add smoked paprika, finely sliced onion and chopped red or yellow peppers, and sauté a bit. Add rice - 100g per serving, 500g of passata and a tin of cherry tomatoes (or fresh ones, if you’ve got some that are a bit too soft to eat raw), and chicken stock - about 75ml for each 100g of rice, I think - but I eyeball it, and add more during cooking if it gets dry. Scrunch up and dampen a piece of grease proof paper, wring it out and flatten on the top of the rice etc, put on a lid, and cook in a medium oven for about 40-45 minutes, instil the rice is cooked.