Slice the English cucumber using a mandolin for thin, uniform pieces.
Add sliced cucumber to a mixing bowl.
Chop the Roma tomato into chunks and add to the bowl.
Thinly slice the red onion and toss it in with the veggies.
Add 2–3 spoonfuls of tzatziki and sprinkle in everything bagel seasoning.
Mix until all vegetables are coated evenly.
Season with salt and freshly ground black pepper.
Crush cashews gently with your hand or the back of a spoon, then sprinkle over the top.
Mix again and serve immediately, or chill in the fridge.