Question: What is the common ingredient in the Bourbon Lancer and the Derby cocktail?

Context paragraphs:
Animal digest: Animal digest is a common ingredient used in pet foods.  As defined by the Association of American Feed Control Officials, digest is produced by the chemical or enzymatic hydrolysis of clean animal tissue that has not undergone decomposition.  These animal tissues may not include hair, horns, teeth, hooves, and feathers, with the exclusion of trace amounts that are unavoidable even after acceptable processing methods.

Derby (cocktail): The Derby is an IBA Official Cocktail composed of gin, peach bitters and mint leaves.

Weisslacker: Weisslacker (German for "whitewashed" due to the rind color), also known as bierkäse and beer cheese, is a type of cow's milk cheese that originated in Germany, but is now known worldwide.  Also produced in the United States, mostly in Wisconsin, it is a pungent and salted surface-ripened cheese that starts out much like brick cheese.  It ripens for seven months in highly humid conditions and is related to Limburger cheese, and has a similarly powerful smell, but paradoxically mild taste.  Connoisseurs of this delicacy often take it with beer (sometimes dipping the cheese directly in their drinks), hence the name.  Many find it too overpowering to serve with wine.  This cheese is also served on small slices of rye or pumpernickel bread often with some sliced onion.  It is a common item on pub and restaurant menus in the Czech Republic, the country with the highest per-capita beer consumption in the world.  This cheese is a common ingredient in various breads, soups, and dips.

Potato doughnut: The potato doughnut, sometimes called a Spudnut, is a doughnut, typically sweet, made with either mashed potatoes or potato starch instead of flour, the most common ingredient used for doughnut dough.  Potato doughnuts were introduced in the mid-1900s, and a recipe was published in 1938.  Potato doughnuts tend to be lighter than flour doughnuts, and are prepared in a similar method to other doughnuts.  A chain of Spudnut Shops was established across the United States in the 1950s before declining to a few dozen more recently.  Fried ube dough is also eaten in East Asia.  Much like flour doughnuts, potato doughnuts are often accompanied with coffee.

Bourbon Lancer: The "Bourbon lancer" is a type of cocktail made by mixing Bourbon whiskey with Champagne.  These are mixed with bitters and served on the rocks.

Sodium selenate: Sodium selenate is the inorganic compound with the formula Na2SeO4 , not to be confused with sodium selenite.  It exists as the anhydrous salt, the heptahydrate, and the decahydrate.  These are white, water-soluble solids.  The decahydrate is a common ingredient in multivitamins and livestock feed as a source of selenium.  The anhydrous salt is used in the production of some glass.  Although the selenates are much more toxic, many physical properties of sodium selenate and sodium sulfate are similar.

Bean sprout: Bean sprouts are a common ingredient across the world.  They are particularly common in Eastern Asian cuisine, made from sprouting beans.

Bagoong monamon: Bagoong monamon, bagoong monamon-dilis, or simply bagoong and bugguong munamon in Ilocano, is a common ingredient used in the Philippines and particularly in Northern Ilocano cuisine.  It is made by fermenting salted anchovies ("monamon" or "munamon" in Ilocano) which is not designed, nor customarily used for immediate consumption since it is completely raw.  Therefore, it is used as a cooking ingredient, upon when it is cooked alone, it can be used as an accompaniment to traditional food dishes.  To most Westerners unfamiliar with this condiment, the smell can be extremely repulsive.  Bagoong is however, an essential ingredient in many curries and sauces.

Bagoong terong: Bagoong Terong or bagoong, and bugguong in the Ilocano language, is a common ingredient used in the Philippines and particularly in Northern Ilocano cuisine.  It is made by salting and fermenting the bonnet mouth fish.  This bagoong is coarser than Bagoong Monamon, and contains fragments of the salted and fermented fish ; they are similar in flavor.  The odor is distinct and unique.  Those who are unfamiliar with this condiment may find the smell repulsive.  Bagoong is an essential ingredient in many curries and sauces.  Fish sauce, common throughout Southeast Asian cuisine, is a by-product of the bagoong process.  Known in the Philippines as "patis", it is distinguished as the clear refined layer floating on the thicker bagoong.  Patis and bagoong can be interchanged in recipes, depending on personal taste and preference.

List of sesame seed dishes: This is a list of notable sesame seed dishes and foods, which are prepared using sesame seed as a main ingredient.  Sesame seed is a common ingredient in various cuisines, and is used whole in cooking for its rich, nutty flavor.

Supporting paragraphs: Derby (cocktail) Bourbon Lancer
Answer: bitters