Nuts (in the culinary sense) and cheese are good for that - a mini-cheeseboard with a couple of different bits of cheese (maybe 20-30g of each), a handful of cashews and walnuts, and maybe a dab of fig jam or membrillo on the side.

Tasty, nutrient-dense, surprisingly filling. Great as a mid-afternoon snack, or add some fruit and a bit of bread or some oatcakes to make it into a decent lunch.