Put a pot of water on to boil for the potatoes and cauliflower.
Peel and chop the onion and garlic; set aside.
Wash and chop the cauliflower into medium-sized pieces; set aside.
Beat the eggs in a medium-sized bowl; set aside. Grate the cheese; stir it into the egg along with a few pinches of dried herbs of your choice; set aside.
In an oven-safe frying pan, heat some oil. Cook the garlic and onion until the onion is soft and translucent.
While the onion is cooking, wash, peel and chop the potato into medium-sized pieces. Add to your pot of boiling water (when it's boiling.) After 10 minutes, pop in the cauliflower as well, and cook for a further two minutes. Then drain, and set aside.
When the onion is soft, fold in the potatoes and cauliflower, and scatter the cherry tomatoes around on top. Set the stovetop heat to medium, then carefully pour the egg and cheese mixture over everything. Cover, and cook for about 10 minutes. At the same time, start your oven's grill / broiler heating (if it needs 10 minutes to heat.)
After 10 minutes on the stove top, remove the cover from the frying pan, and pop the frittata under your oven's grill / broiler until the top is browned and set -- about 5 to 8 minutes.