For steeped grains plus malt extract:
2021 BJCP 18B - Czech lager: Premium pale characteristic ingredients: "Traditional Czech hops. Czech malt. Czech lager yeast. Water low in sulfate and carbonate provides a distinctively soft, rounded hop profile despite high hopping rates. The bitterness level of some larger commercial examples has dropped in recent years, although not as much as in many contemporary German examples."
Vital Statistics: OG: 1.044 – 1.060, IBUs: 30 – 45, FG: 1.013 – 1.017, SRM: 3.5 – 6, ABV: 4.2 – 5.8%
The iconic commercial example of this style is Pilsner Urquell. The introduction of this beer in the mid-1800s revolutionized brewing to make pale lager beers a world-wide standard.
The brewing water needs to be soft, low in carbonates and sulfates. The pH may need special attention. Decoction mashes are traditional, but some experts feel that a good example can be brewed with standard infusion or step mashes.
The base grain is a continental pilsner malt, such as Weyermann or Moravian pilsner malt. Small amounts (about 5%) of very light crystal malt may increase foam and body. Acidulated malt is optional for achieving a proper mash pH. Most light malt extracts are based upon pilsner malt and may already have small amounts of light specialty malts such as CaraPils.
The Czech Saaz hop is a defining feature. Possible substitutes are American-grown Saaz or Sterling (a hop bred from Saaz). Magnum is sometimes used for bittering. Most of the reviewed premium pilsner recipes have three or four hop additions, but no dry hopping. A BU/GU ratio of .75 is recommended.
There are several liquid Czech lager yeasts to choose from. German lager yeasts like W34-70 might be acceptable substitutes.
Beer-analytics.com Czech lager premium pale analyses
2021 BJCP 03 - Czech lager styles
Dornbusch, H. (2004, March-April). Bohemian pilsner: The world's first blond lager. BYO, p. 21 - 24.
Dornbusch, H. (2008, May - June). Czech pilsner: Recreating a brew revolution. BYO, p. 40 - 45.
Strong, G. (2014, November). Bohemian pilsner: Brewing the classic pale lager of the Czech Republic. BYO, p. 59 - 66.
Strong, G. (2015, May-June). The everyday Czech pale lager: The newest addition to the BJCP style guide. BYO, p. 30 - 35.
Zainasheff, J. (2009, November). Bohemian pilsner: Crisp, balanced, and spicy. BYO, p. 19 - 23.