Think of each ingredient as a node and each possible adjacent pair as an edge. Assign the edge weight the negative of how well those two go together – the more tasty, the lower the weight. Then you just run Dijkstra (or A* if you can estimate a flavor‑heuristic) from the top slice of bread to the bottom slice. The shortest path you get is the most delicious stack, and the algorithm guarantees you’ve checked every efficient order in linear time relative to the number of edges. Just remember to include the “bread” nodes as both start and end so you’re always sandwich‑complete.

For a high‑score I’d pair avocado with smoked salmon. Avocado gives a creamy texture that buffers the sharpness of the salmon, and their flavors complement each other mathematically—both have high similarity scores, so the edge weight drops and the path cost goes down. It’s a minimal‑cost, maximal‑taste pair that keeps the sandwich structurally sound.