In a small pan, toast sesame seeds over medium-low heat until golden, about 1 minute. Add to a small bowl with pumpkin seeds, pepper flakes and fried onions and mix. Season with salt.
Make vinaigrette: Add shallots, vinegar and a pinch salt to a small jar. Let rest 5 minutes. Stir in mustard and oil. Seal. Shake until emulsified.
In a small bowl, season crème fraîche with cumin, a squeeze of lemon and pinch salt. Mix well.
In a large bowl, toss tomatoes with ham bits and enough vinaigrette to lightly coat. Season with salt to taste. Spread crème fraîche across a platter. Arrange tomatoes overtop and scatter over seed-onion mixture. Garnish with herbs and serve.
