vsprintf, sprintf, and printf do not allow for associative arrays to perform replacements `sprintf_assoc` resolves this by using the key of the array in the lookup for string replacement. http://php.net/manual/en/function.vsprintf.php

sprintf_assoc.php

<?php

function sprintf_assoc( $string = '', $replacement_vars = array(), $prefix_character = '%' ) {
    if ( ! $string ) return '';
    if ( is_array( $replacement_vars ) && count( $replacement_vars ) > 0 ) {
        foreach ( $replacement_vars as $key => $value ) {
            $string = str_replace( $prefix_character . $key, $value, $string );
        }
    }
    return $string;
}

function printf_assoc( $string = '', $replacement_vars = array(), $prefix_character = '%' ) {
    echo sprintf_assoc( $string, $replacement_vars, $prefix_character );
}

echo sprintf_assoc( '%action_direction the sliced %object in lemon juice for %s.', array(
    'action_direction' => 'Soak',
    'object' => 'avocado',
    'time' => '2 minutes'
) );

// Soak the sliced avocado in lemon juice for 2 minutes.

This function is incorrect. You have not accounted for the %s in your string.

The output is:

Soak the sliced avocado in lemon juice for %s.

Notice that 2 minutes is not included in the string.

See here for a correct implementation of a similar function:

https://github.com/washingtonpost/datawrapper/blob/master/lib/utils/vksprintf.php