Given the following R code, how can I first evaluate the inline R code inside the string and next parse it for markdown?

foo <- 6
bar <- "kg"
str = "The *value* is `r foo` DKK per `r bar`"
# Now evaluate the inline r
cat(markdown::mark_html(str))
# output wanted for the <p> tag: <p>The <em>value</em> is 6 DKK per kg</p>
# and not <p>The <em>value</em> is <code>r foo</code> DKK per <code>r bar</code></p>