[Xiaomi Mi 5s Plus ROMs, Kernels, Recoveries, & Oth] rodries:
You have to download the rom and uncompress it. Then go to fastboot mode and execute this commands from a command window.

The other way is download the recovery zip format of the ROM (http://en.miui.com/download-315.html) uncompress, change META-INF\com\google\android\updater-script to remove a few files to avoid to flash system, compress it again and install it in recovery.

get_device_compatible("natrium") == "OK" || abort("This package is for \"natrium\" devices; this is a \"" + getprop("ro.product.device") + "\".");
ui_print("Target: Xiaomi/natrium/natrium:6.0.1/MXB48T/7.4.14: Firmware update");
show_progress(0.100000, 5);
ui_print("Patching firmware images...");
package_extract_file("firmware-update/cmnlib64.mbn", "/dev/block/bootdevice/by-name/cmnlib64");
package_extract_file("firmware-update/cmnlib.mbn", "/dev/block/bootdevice/by-name/cmnlib");
package_extract_file("firmware-update/hyp.mbn", "/dev/block/bootdevice/by-name/hyp");
package_extract_file("firmware-update/pmic.elf", "/dev/block/bootdevice/by-name/pmic");
package_extract_file("firmware-update/tz.mbn", "/dev/block/bootdevice/by-name/tz");
package_extract_file("firmware-update/emmc_appsboot.mbn", "/dev/block/bootdevice/by-name/aboot");
package_extract_file("firmware-update/lksecapp.mbn", "/dev/block/bootdevice/by-name/lksecapp");
package_extract_file("firmware-update/devcfg.mbn", "/dev/block/bootdevice/by-name/devcfg");
package_extract_file("firmware-update/keymaster.mbn", "/dev/block/bootdevice/by-name/keymaster");
package_extract_file("firmware-update/xbl.elf", "/dev/block/bootdevice/by-name/xbl");
package_extract_file("firmware-update/rpm.mbn", "/dev/block/bootdevice/by-name/rpm");
package_extract_file("firmware-update/cmnlib64.mbn", "/dev/block/bootdevice/by-name/cmnlib64bak");
package_extract_file("firmware-update/cmnlib.mbn", "/dev/block/bootdevice/by-name/cmnlibbak");
package_extract_file("firmware-update/hyp.mbn", "/dev/block/bootdevice/by-name/hypbak");
package_extract_file("firmware-update/pmic.elf", "/dev/block/bootdevice/by-name/pmicbak");
package_extract_file("firmware-update/tz.mbn", "/dev/block/bootdevice/by-name/tzbak");
package_extract_file("firmware-update/emmc_appsboot.mbn", "/dev/block/bootdevice/by-name/abootbak");
package_extract_file("firmware-update/lksecapp.mbn", "/dev/block/bootdevice/by-name/lksecappbak");
package_extract_file("firmware-update/devcfg.mbn", "/dev/block/bootdevice/by-name/devcfgbak");
package_extract_file("firmware-update/keymaster.mbn", "/dev/block/bootdevice/by-name/keymasterbak");
package_extract_file("firmware-update/xbl.elf", "/dev/block/bootdevice/by-name/xblbak");
package_extract_file("firmware-update/rpm.mbn", "/dev/block/bootdevice/by-name/rpmbak");
package_extract_file("firmware-update/splash.img", "/dev/block/bootdevice/by-name/splash");
package_extract_file("firmware-update/NON-HLOS.bin", "/dev/block/bootdevice/by-name/modem");
package_extract_file("firmware-update/logo.img", "/dev/block/bootdevice/by-name/logo");
package_extract_file("firmware-update/adspso.bin", "/dev/block/bootdevice/by-name/dsp");
package_extract_file("firmware-update/BTFM.bin", "/dev/block/bootdevice/by-name/bluetooth");
package_extract_file("META-INF/com/miui/miui_update", "/cache/miui_update");
set_metadata("/cache/miui_update", "uid", 0, "gid", 0, "mode", 0555, "capabilities", 0x0);
run_program("/cache/miui_update");
delete("/cache/miui_update");
show_progress(0.100000, 2);
ui_print("Done!");

In the zip file you need firmware-update & META-INF folders only.

PD: I can give to you a link with the recovery zip file in private.