When in SaPa, few tourists seek to eat at the local market.
Most, it appears, wander around the market for a 'look see', or use the southern pathway as a route from P. Cau Mai to D. Phan Si. (ie. from the main tourist drag to the street that goes to Cat Cat).
If you go 'into' the centre of the wet and dry goods area, you'll note quite a few food vendors.
One with a long table (at the Cat Cat side) will invariably have a number of H!Mong eating Pho.
With limited money, locals tend to favour good value & good flavoured food.
This vendor offers a great Pho (15,000VNdong), and the evening meals are superb.
No wonder it is only this vendor that gets the H!Mong 'vote of approval'!
If asked, they will serve you a really good cup of Ca Fe Sua (Vietnamese coffee with condensed milk).