Make the momos:
Make the dough for the momo wrappers, by placing the flour in a bowl with the salt and oil. Add a little water at a time and knead to make a fairly pliable dough.
Set the dough aside for about 30 minutes to relax.
To make the filling, heat the oil in a saucepan.
Add all the vegetables except the artichokes and spring onions. Add salt and ground black pepper to taste. Add ginger and garlic.
Cook over high heat, stirring frequently, until all the moisture from the vegetables have evaporated and they are tender.
Add the artichoke hearts and spring onions and cook until they are just tender, 2-3 minutes.
Add soy sauce and more salt if needed. Turn off the heat.
To assemble the momos, divide the dough into 12 equal pieces. Roll each piece into a smooth ball, then roll it out into a circle about 3 inches in diameter.
Place 2 heaping tbsp of the filling in the center of the circle.
Pick up one end of the wrapper and start forming the momo by pinching the edges up to the top, pleating them as you go. Once you've gathered all of the edges, ping them together at the top to seal them. You can also just make half-moon shapes by placing the filling slightly off-center, then folding one half of the circle over the other, and crimping the edges together with a fork.
Heat some water in a pot fitted with a steamer. You can just use any vegetable steamer for this. Brush or spray the steamer with some oil to prevent the momos from sticking.
When the water comes to a boil, lower the heat to a simmer, arrange the momos in the steamer basket, making sure you leave at least 1/2 an inch between them.
Cover tightly and steam the momos for 9 minutes. The wrappers will turn translucent when they're ready.
Remove and serve hot with the red sauce.
How to make red sauce:
Place the tomatoes in a foil-lined baking sheet. Cut off the top of the garlic bulb so the tops of the cloves are exposed, wrap the bulb in foil, and place next to the tomatoes.
Roast in a 400-degree oven for 30 minutes.
In a skillet, dry-roast the red chilies until they darken a shade or two.
Place the roasted tomatoes, garlic (discard the skins) and chilies in a blender. Zap until you have a fairly smooth sauce.
Remove to a bowl and serve with the momos.