I admit I had a mustard sandwich before (with cheese) but only because I ran out of lunch meat and was too lazy to make anything else.
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A mustard sandwhich with bread and cheese tastes good
A sandwhich with mustard and bread and nothing else tastes bad
A sandwhich with mustard tomatoes and bread and nothing else tastes bad
Plain bread with nothing on it sometimes tastes better than bread with only mustard
it's an acquired taste
baguette with sriracha