This is my take on a Shepherd's Pie with more of a spiced cumin/coriander flavor than the traditional garlic/herbal take. By default it is low-FODMAP and dairy and gluten-free.
Equipment
You may be able to get away with substitutes for many of these, but this is what I use.
Large pot for boiling potatoes
Large ~12 inch [~30 cm] cast iron skillet, seasoned
Something to cover the skillet with, like a large pot lid
Hard metal spatula
Stirring spoon or spatula
Strainer/colander
Fork
Chef's knife
Peeler
Cutting board
Stove
Oven
Ingredients
For the filling:
1/3-1/2 cup [~100 ml] loosely packed fresh coriander leaves (remove stems before measuring)
1 medium-sized Yukon gold potato (additional to the potatoes for the crust)
Optional: 1 yellow onion (not low-FODMAP)
~8 ounces [~250 ml] low-FODMAP beef stock (Tabatchnick brand appears not to contain onions or garlic)
1-2 Tbsp [~25 ml] red wine
~1 Tbsp [~15 ml] fresh ground black pepper
~2 tsp [~10 ml] ground cinnamon
~2 Tbsp [~30 ml] Diamond Crystal kosher salt or ~4 tsp [~20 ml] Morton's kosher salt (to taste)
1/4 cup [~ 60 ml] potato starch or all-purpose flour (contains gluten)
Optional: Ground red pepper, pepper flakes, or cayenne for spice
Optional: Garlic powder (not low-FODMAP)
For the Mashed Potato Crust:
2 medium russet potatoes
1 medium Yukon gold potato (in addition to the potato in the filling)
~2 gallons [~7.5 liters] water for boiling
Salt to taste
Fresh ground black pepper to taste
Optional: Garlic powder (not low-FODMAP)
Extra virgin olive oil or butter (contains dairy)
Unsweetened, unflavored almond milk or cow's milk (contains dairy)
Directions
Before anything else:
Preheat your oven to 425°F [~220°C]
Put the water for the potatoes on to boil
Prep work (while you wait):
Wash and peel the carrots and potato (and onion if you're using one) for the filling
Dice the filling potato into cubes about 1/2 inch [~1 cm] on each side
Cut the carrots into circles or semicircles about twice the total size of the potato cubes
Wash the pepper and remove the core and the seeds
Cut the pepper into ~1 inch by 1/3 inch [~3 cm by 3/4 cm] strips
Remove the stems from the coriander and mince the leaves
Wash and peel the potatoes for the crust (you can leave about half the peel from the Yukon gold potato on)
Cut the potatoes into large-ish chunks (maybe 6-8 evenly sized chunks per medium potato)
Cooking the crust (mostly in parallel with the filling):
Once the water in boiling, add potatoes and stir (salt can be added later)
Let them boil for 20 minutes
Potatoes are done when the russet potatoes just barely split in half when you stab them through with a fork (Yukon gold potatoes will be a bit more robust)
Mash the potatoes with a fork, adding the other ingredients to taste
Russet potatoes should be smooth, and Yukon gold potatoes add a little texture
Cooking the filling (mostly in parallel with the crust):
Put oil or fat in your skillet until it just barely covers the bottom (tilt the skillet to cover more area while using less oil)
Turn the stove on medium-low heat
Sprinkle cumin and mustard seeds into the pan to toast them
Cover the pan because the seeds will pop and fly like popcorn
Turn the heat down and remove the cover occasionally to stir the seeds
When the seeds start to brown, add lamb, coriander, salt, and black pepper
Cook, stirring frequently, until there isn't much or any pink left in the lamb
Add potatoes, carrots, bell pepper, cinnamon, and whatever other spices you might be using
Stir and let the potatoes start to brown
Add the wine and beef stock
Turn the heat up to medium and keep stirring
Let the liquid boil down a bit (about 5 minutes)
Add the potato starch slowly to soak up remaining liquid, stirring to prevent clumping
Turn off the heat
Combining and final steps:
Spread the mashed potatoes over the filling in the skillet with a soft rubber of silicone spatula
Mark where the crust will be sliced with the spatula