  Lascoux polynomials are $K$-theoretic analogues of the key polynomials. They
both have combinatorial formulas involving tableaux: reverse set-valued
tableaux ($\mathsf{RSVT}$) rule for Lascoux polynomials and reverse
semistandard Young tableaux ($\mathsf{RSSYT}$) rule for key polynomials.
Furthermore, key polynomials have a simple algorithmic model in terms of
Kohnert diagrams, which are in bijection with $\mathsf{RSSYT}$. Ross and Yong
introduced $K$-Kohnert diagrams, which are analogues of Kohnert diagrams. They
conjectured a $K$-Kohnert diagram rule for Lascoux polynomials. We establish
this conjecture by constructing a weight-preserving bijection between
$\mathsf{RSVT}$ and $K$-Kohnert diagrams.
