It's really up to you to go out and find them. I suggest looking for local meetups and talking to engineers who are working in those small businesses. Get to know the people in your community running these small businesses.

Most of our hires were introduced through people I know. In a small business this is often the only logical way to hire because you already have some level of trust with the referrer and thus they've acted as the first gateway for a candidate to get through (and they usually can vouch for the candidate's work).

Also, many small businesses are concerned largely with staying alive and making a profit, so that may mean they will be focused on "non-interesting" problems of making the business operate well. Factor this into your decision as to who you want to work for as well.